Answer:
4.74
Explanation:
It is possible to find pH of a buffer (The mixture of a weak acid: Acetic acid, with its conjugate base: Sodium acetate) using Henderson-Hasselbalch equation:
pH = pKa + log₁₀ [A⁻] / [HA]
Where pKa is -log Ka of the weak acid, [A⁻] concentration of the conjugate base and [HA] concentration of the weak acid
pKa of acetic acid is -log 1.8x10⁻⁵ = 4.74
The concentration of both, acetic acid and sodium acetate is 0.1M. Replacing in H-H equation:
pH = pKa + log₁₀ [A⁻] / [HA]
pH = 4.74 + log₁₀ [0.1] / [0.1]
pH = 4.74 + log₁₀ 1
pH = 4.74
Theoretical pH is 4.74
(03.01 LC
Which of the following is not present in an atom? (1 point)
Answer:
Protons, Neutrons, and Electrons are all in atoms so the one not present would be the Element since Elements are made of atoms.
Explanation:
How have safety concerns about chemicals changed over time?
A. Government officials rather than scientists decide what chemicals
are dangerous.
B. All nations have agreed to a set of safety standards, so testing
chemicals is no longer necessary.
C. As scientists have learned more about chemicals, they have
become more aware of their dangers.
D. Scientists are no longer as concerned about chemicals because
they are much safer today.
Answer:
C. As scientists have learned more about chemicals, they have become more aware of their dangers
Explanation:
Chemicals are substances with standard compositions, held together by chemical bonds. Chemicals can exist in different phases such as solid, liquid, and gaseous phases. Over time, with a growing understanding of chemicals, their composition, and their reaction methods, scientists now have a better knowledge of the dangers chemicals can pose. To that effect, they have created standard safety measures for those who have to work with these chemicals.
When these guidelines are strictly adhered to, the chances of suffering accidents, burns, and explosions with these chemicals are significantly reduced.
Rank the following transitions in a hydrogen atom in order of increasing wavelength of electromagnetic radiation that could produce them. Answer this question without doing any calculations. Explain the order.
n=2 to n=4
n=6 to n=8
n=10 to n=12
n=14 to n=16
Answer:
n=2 to n=4 < n=6 to n=8 < n=10 to n=12 < n=14 to n=16
Explanation:
According to Neils Bohr, electrons in an atom are found in specified energy levels. Transitions are possible from one energy level to another when the electron receives sufficient energy usually in the form of a photon of electromagnetic radiation of appropriate frequency and wavelength. The energy of this photon corresponds to the energy difference between the two energy levels. Thus the higher the energy difference between energy levels, the greater the energy of the photon required to cause the transition and the shorter the wavelength of the photon.
High energy photons have a very short wavelength. It should be noted that as n increases, the energy of successive energy levels decreases and transitions between them now occurs at longer wavelengths. Hence, the highest energy and shortest wavelength of photons are required for transition involving lower values of n because such electrons are closer to the nucleus and are more tightly bound to it than electrons found at a greater distance from the nucleus.
Hence transition involving electrons at higher energy levels occur at a longer wavelength compared to transition involving electrons closer to the nucleus. This is the basis for the arrangement of wavelengths required to effect the various electronic transitions shown in the answer.
Enter an abbreviated electron configuration for magnesium: Express your answer in complete form, in order of increasing energy. For example, [He]2s22p2 would be entered as [He]2s^22p^2.
Answer:
[Ne]3s²
Explanation:
Mg
1s2 2s2 2p6 3s2 or [Ne]3s²
Abbreviated electronic configuration of magnesium is [Ne]3 s² and in complete form it is 1 s² 2 s² 2 p⁶ 3 s².
What is electronic configuration?Electronic configuration is defined as the distribution of electrons which are present in an atom or molecule in atomic or molecular orbitals.It describes how each electron moves independently in an orbital.
Knowledge of electronic configuration is necessary for understanding the structure of periodic table.It helps in understanding the chemical properties of elements.
Elements undergo chemical reactions in order to achieve stability. Main group elements obey the octet rule in their electronic configuration while the transition elements follow the 18 electron rule. Noble elements have valence shell complete in ground state and hence are said to be stable.
Learn more about electronic configuration,here:
https://brainly.com/question/13497372
#SPJ5
Q#1 Give a combination of four quantum numbers that could be assigned to an electron occupying a 5p orbital.
Express your answers using one significant figures. Enter your answers separated by commas.
The answer n, l, ml, ms = 5,1,-1,0,or1,-1/2or+1/2
mastring chemistry says
"Incorrect; Try Again; 6 attempts remaining; no points deducted
Your answer does not have the correct number of comma-separated terms."
the same for q#2
Do the same for an electron occupying a 6d orbital.
Express your answers using one significant figures. Enter your answers separated by commas.
the answer n, l, ml, ms =6,0,1,2,-2,-1,0,+1,+2,+1/2or-1/2
Answer:
For an electron in 5p orbital
5,1,-1,+1/2
For an electron in 6d orbital
6,2,-2,+1/2
Explanation:
The term quantum numbers refers to a set of values that can be used to determine the region in space where it is likely to find an electron. This region in space where there is a high probability of finding an electron is known as an atomic orbital. An atomic orbital is actually a wave function according to the Schrödinger wave equation.
There are four quantum numbers used in describing an atomic orbital: the principal quantum number (n), the orbital angular momentum quantum number also called azimuthal or subsidiary quantum number (l), the magnetic quantum number (ml), and the electron spin quantum number (ms).
For a 5p orbital;
n= 5, l= 1, ml= -1,0,1 ms= +1/2 or -1/2
For 6d orbital;
n= 6, l= 2, ml= -2,-1,0,1,2, ms= +1/2 or -1/2
Since we are requested to use a four quantum number description that can be assigned to an electron in these levels;
For an electron in 5p orbital
5,1,-1,+1/2
For an electron in 6d orbital
6,2,-2,+1/2
Calculate ΔG (in kJ) for the following reaction at 1.0 atm for C2H6, 0.5 atm for O2, and 2.0 atm for CO2, and 25 oC: C2H6 (g) + O2 (g) ---> CO2 (g) + H2O (l) (unbalanced) ΔGfo C2H6 (g) = - 32.89 kJ/mol; ΔGfo CO2 (g) = - 394.4 kJ/mol; ΔGfo H2O (l) = - 237.13 kJ/mol
Answer:
Explanation:
Calculate ΔG (in kJ) for the following reaction at 1.0 atm for C2H6,
0.5 atm for O2, and
2.0 atm for CO2, and
25 oC:
C2H6 (g) + O2 (g) ---> CO2 (g) + H2O (l) (unbalanced)
ΔGfo C2H6 (g) = - 32.89 kJ/mol;
ΔGfo CO2 (g) = - 394.4 kJ/mol;
ΔGfo H2O (l) = - 237.13 kJ/mol
The balance equation of this reaction is
[tex]2C_2H_6 (g) + 7O_2 (g) ---> 4CO_2 (g) + 6H_2O (l)[/tex]
[tex]\Delta G_{rxn}=\sum G^o_f(product)-\sum G^o_f(reactant)[/tex]
[tex]=4G^o_f(CO_2)+6G^o_f(H_2O)-7G^o_f(O_2)-2G^o_f(C_2H_6)\\\\[/tex]
[tex][4(-394.4)+6(-237.13)-7(0)-2(-32.89)]kJ/mol\\\\=-1577.6-1422.78+65.78\\\\=-3000.38+65.78\\\\=-2934.6kJ/mol[/tex]
g If a sample of 50 mL of ethyl benzene (bp = 136 C) was contaminated with 10 mL of ethyl acetate (bp = 77 C) what effect would this have on the boiling point measurement?
Answer:
melting point will be higher than that of pure ethyl acetate
Explanation:
During lab, students mixed two solutions of soluble ions in a ceramic well to determine if a precipitate forms.
Write the dissolution reaction for the ionic solids below. (Use the lowest possible coefficients. Include states-of-matter under the given conditions in your answer.)
(a) Ca(NO3)2
(b) Na3PO4
The two solutions, when mixed, will have two cations and two anions.
(c) Based on your lab results, enter the cation and anion for which a precipitate will form. (Separate substances in a list with a comma.)
(d) Write the net precipitation reaction that occurs. (Use the lowest possible coefficients. Include states-of-matter under the given conditions in your answer.)
Answer:
(a) [tex]Ca(NO_3)_2(s)\rightarrow Ca^{2+}(aq)+2NO_3^-(aq)[/tex]
(b) [tex]Na_3PO_4(s)\rightarrow 3Na^++PO_4^{3-}[/tex]
(c) [tex]Ca^{2+} \ and \ PO_4^{3-}[/tex]
(d) [tex]3Ca^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Ca_3(PO_4)_2(s)[/tex]
Explanation:
Hello,
In this case, the balanced dissolution reactions are:
(a) [tex]Ca(NO_3)_2(s)\rightarrow Ca^{2+}(aq)+2NO_3^-(aq)[/tex]
(b) [tex]Na_3PO_4(s)\rightarrow 3Na^++PO_4^{3-}[/tex]
Moreover, when calcium nitrate and sodium phosphate react a double displacement reaction occurs, forming calcium phosphate, which is actually the precipitate due to its low solubility in water, and sodium nitrate:
[tex]2Na_3PO_4(aq)+3Ca(NO_3)_2(aq)\rightarrow 6NaNO_3(aq)+Ca_3(PO_4)_2(s)[/tex]
Thus, the precipitate is formed by:
(c) [tex]Ca^{2+} \ and \ PO_4^{3-}[/tex]
Finally, the net precipitation reaction shows the involved cation, anion and final product:
(d) [tex]3Ca^{2+}(aq)+2PO_4^{3-}(aq)\rightarrow Ca_3(PO_4)_2(s)[/tex]
Regards.
Given the following Fischer projection: Fischer projection for an entantiomer of 2-bromo-2,3-dihydroxypropanal with the bromine oriented horizontally to the left and the hydroxide group oriented horizontally to the right. draw the perspective formula of the molecule. Be sure to correctly indicate stereochemistry in your answer.
Answer:
Explanation:
Stereoisomers are two or more atoms that have the same bonding order of atoms but there is a difference spatial arrangement of the atoms in space.
A plane of symmetry divides a molecule into two equal halves.
A chiral stereoisomer are not superimposed on a mirror image , Hence they do not posses a plane of symmetry.
As a result to that. these non-superimposable mirror images are said to be Enantiomers.
However, a Fischer Projection emanates from a two - dimensional figure which is used for presenting a three - dimensional organic molecules.
From the given question;
Fischer projection for an enantiomer of 2-bromo-2,3-dihydroxypropanal with the bromine oriented horizontally to the left and the hydroxide group oriented horizontally to the right.
we can sketch the way the enantiomer of 2-bromo-2,3-dihydroxypropanal can be seen like the one shown below:
CH₂OH
|
|
|
Br -------------|----------------OH
|
|
|
CHO
The objective of this question is to drawn the perspective formula of the molecule.
So , from the attached file below; we can see the perspective formula of the molecule in a well structured 3-D format.
the options are: ( it can’t be repeated )
1-synthetic polymer
2-natural polymer
3-gamma radiation
4-condensation polymerization
5-addition polymerization
Answer:
3- gamma radiation
Explanation:
Hello,
In the above question, 4 of the options are related to polymerization which are
1. Synthetic polymer
2. Natural polymer
3. Condensation polymerization
4. Addition polymerization.
The first two options are types of polymer that exists while the last two are polymerization techniques.
The odd option here which is "gamma radiation" is a particle which is emitted from radioactive substances during decay. It has no mass and no charge but it is highly penetrating and dangerous to human health.
However,
Synthetic polymers are also known as man made polymers and they exist around us because they're present in materials which we use everyday. An example is polyethylene, nylon-6,6 etc
Natural polymers are compounds which are polymeric in nature (compounds catenating to form a complex molecule). Natrual occurring polymers can be found in proteins and some lipids.
AMMONIUM CARBONATE
5. How many grams of nitrogen (N) are in a mass of ammonium carbonate that contains
1.23x10^23 carbon atoms?
Answer:
Zero
Explanation:
Hello,
The question require us to calculate the mass of nitrogen present in aluminium carbonate.
This can easily be calculated using Avogadro's number as a constant with some minor calculations but however in this case, we can't because there's no single atom of nitrogen present in aluminium carbonate hence we can't calculate the mass of nitrogen present in it.
Chemical formula of aluminium carbonate = Al₂(CO₃)₃.
From the above chemical formula, we can see that there's no single atom of nitrogen present in the formula hence the mass of nitrogen present in aluminium carbonate that contains 1.23×10²³ carbon atoms is zero.
Consider each of the following molecules in turn: (a) dimethyl ether, (CH3)2O; (b) trimethylamine, (CH3)3N; (c) trimethylboron, (CH3)3B; and (d) carbon dioxide (CO2). Describe the hybridization state of the central atom (i.e., O, N, B, or C) of each molecule, tell what bond angles you would expect at the central atom, and state whether the molecule would have a dipole moment.
Answer:
Consider each of the following molecules in turn: (a) dimethyl ether, (CH3)2O; (b) trimethylamine, (CH3)3N; (c) trimethylboron, (CH3)3B; and (d) carbon dioxide (CO2). Describe the hybridization state of the central atom (i.e., O, N, B, or C) of each molecule, tell what bond angles you would expect at the central atom, and state whether the molecule would have a dipole moment.
Spell out the full name of the compound.
Explanation:
Step one look for the longest chain of carbon atoms
Longest chain is 7 C atoms
Step 2 look for double bonds or others functional groups
it is present in 3rd carbon
Therefore IUPAC name is 3-heptene
From point of stereochemistry it can also be written as trans-3-heptene as the hydrogens are placed in opposite side of the C=C bond.
Hope this helps...
The compound name is: trans 3-heptene
What is molecular compound?Molecular compounds are inorganic compounds that take the form of discrete molecules.
Looking at the given compound:
1. We need to look for the highest carbon chain, So in this compound the highest carbon chain is of 7 carbon atoms.
2. This compound also has a double bond in between that is present at the third carbon which can be detected by numbering the carbon in a order where the lowest number will come over a double bond.
3. Lastly, we can derive the name for this compound as hept-3-ene or 3-heptene.
4. Also, there is one more thing to notice here which is the position of two hydrogen that are present as substituents since they are placed opposite to each other thus we can name it as trans 3-heptene.
Thus, the compound name is: trans 3-heptene.
Find more information about Compound here:
brainly.com/question/1603500
For each of the following pairs of elements
(1C and N2) (1Ar and Br2)
pick the atom with
a. more favorable (exothermic) electron affinity.
b. higher ionization energy.
c. larger size.
How do you even go about do this?
Explanation:
Electron affinity is defined as the energy released by the addition of an electron to any gaseous atom. Electron affinity of an atom depends on the electronic configuration.
a).The carbon has vacant p-orbital and nitrogen has half-filled configuration which is more stable. Therefore, one electron can be easily added to carbon whereas nitrogen having more stable configuration releases more amount of energy on adding one electron. Therefore, nitrogen has more electron affinity than carbon.
The bromine has vacant p-orbital whereas argon has filled orbital which is most stable. Therefore, one electron can be easily added to bromine whereas argon having more stable configuration releases more amount of energy on adding one electron.Therefore, argon has more electron affinity than bromine.
Answer:
1. a. C; b. N; c. C; 2. a. Br; b. Ar; c. Br
Explanation:
Use your Periodic Table and follow the trends in atomic properties (Fig. 1).
Electron affinity increases from left to right and from bottom to top.
The elements with the most exothermic EA are at the upper right corner
Exceptions are the noble gases (group 18) and the pnictogens (group 18).
The elements of Group 18 have a complete octet and have no tendency to accept electrons.
The elements of Group 15 have half-filled p subshells. They are more stable than the elements immediately preceding them, so they are less exothermic when adding an electron.
Ionization energy increases from left to right and from bottom to top.
The atoms with the highest IE are at the upper right corner.
Atomic size increases from right to left and from bottom to top.
The largest atoms are on the lower-left corner.
1. C vs N
(a) EA: C. N is a Group 15 element
(b) IE: N. N is further to the right.
(c) Size: C. C is further to the left.
2. Ar vs Br
(a) EA: Br. Ar is a noble gas.
(b) IE: Ar. Ar is further to the right.
(c) Size: Br. Br is nearer to the bottom.
The first three excited states of the nucleus Au-199 (gold) are at 0.075 Mev, 0.320 Mev and 0.475 MeV. If all transitions between theses states and the ground state occurred, what energy/wavelength gamma rays would be observed?
Answer and Explanation:
The computation of the energy or wavelength gamma rays observed is shown below:
Since the energy of gamma rays is higher than 0.10 MeV.
Now We have to calculate transitions in between the given levels of energy that correspond to this energy.
As per the given question, we have the following information
Ground state = E where E < 0.075 MeV
For Level 1 = 0.075 MeV
For Level 2 = 0.320 MeV
For Level 3 = 0.475 MeV
Now we have to take the below transitions:
1. [tex]3 \rightarrow 2[/tex]
Difference of energy is
= 0.475 - 0.320
= 0.155 MeV
This represents a gamma radiation
2. [tex]3 \rightarrow 1[/tex]
Difference of energy is
= 0.475 - 0.075
= 0.4 MeV
This represents a gamma radiation
3. [tex]3 \rightarrow ground[/tex]
Difference of energy is
= 0.475 - E > 0.155 MeV
This represents a gamma radiation
4. [tex]2 \rightarrow 1[/tex]
Difference of energy is
= 0.320 - 0.075
= 0.245 MeV
This represents a gamma radiation
5. [tex]2 \rightarrow ground[/tex]
Difference of energy is
= 0.320 - E > 0.245 MeV
This represents a gamma radiation
6. [tex]1 \rightarrow Ground[/tex]
Difference of energy is
= 0.075 - E < 0.10 MeV
This represents not a gamma radiation
We can see that there are 5 transitions that contain gamma rays
How many elements make up most of the ocean?
Answer:
Hydrogen and oxygen
Explanation:
Answer:
eight
Explanation:
the elements of course are the following
hydrogen
oxygen
calcium
sodium
sulfur
magnesium
chlorine
potassium
i hope this helps you
Hands moving on a battery-operated clock is an example of what kind of
energy conversion?
A. Kinetic energy being converted to chemical potential energy
B. Gravitational potential energy being converted to heat energy
C. Heat energy being converted to gravitational potential energy
O
D. Chemical potential energy being converted to kinetic energy
Answer: D. Chemical potential energy being converted to kinetic energy
Explanation: Batteries are chemical and that energy is converted into kinetic to make the hands on the clock move :) hope this helped!
What is the law of conservation and what happens when two substances at different temperatures come into contact.
Answer:
- Both energy and matter cannot be neither created nor destroyed.
- An equilibrium temperature will be reached.
Explanation:
Hello,
In this case, the law of conservation is applied to both matter and energy, and it states that both energy and matter cannot be neither created nor destroyed. Specifically, in chemical reactions, it states that in closed systems, the mass of the reactants equals the mass of the products even when the number of moles change. Moreover, for energy, if two substances at different temperatures come into contact, the hot one will cool down and the cold one will heat up until an equilibrium temperature so the energy lost by the hot one is gained by the cold one, which accounts for the transformation of energy.
Best regards.
Nitrosyl bromide, NOBr, is formed from NO and Br2.
2 NO(g) + Br2(g) 2 NOBr(g)
Experiments show the reaction is second order in NO and first order in Br2.
How does the reaction rate change if the concentration of Br2 is changed from 0.0022 mol/L to 0.0066 mol/L?
a) the rate will double
b) the rate will remain unchanged
c) the rate will triple
Answer:
C ) The rate will triple
Use the link Standard Reduction Potentials. Write net equations for the spontaneous redox reactions that occur during the following or none (all lower case) if there is no extensive reaction. Use the lowest possible coefficients. A) Iron metal is dipped into a Ni2+ solution.B) Copper metal is added to hydrochloric acid.C) A silver wire is added to nitric acid (HNO3).D) Magnesium metal is added to waterE) Chromium metal is added to a solution of Mg2+
Answer:
a) Fe(s) + Ni^2+(aq) ----> Fe^2+(aq) + Ni(s)
b) no reaction
c) no reaction
d) 2Mg(s) + 2H2O(l)-----> 2Mg^2+(aq) + O2(g) +4H^+(aq)
e) no reaction
Explanation:
It is important to say here that the ability of a particular chemical specie to displace another chemical specie is dependent on the relative standard reduction potentials of the species involved.
All the reactions stated above are redox reactions. Let us take reaction E as an example. Mg^2+ has a reduction potential of -2.37 V while Cr^3+ has a reduction potential of -0.74V. Since the reduction potential of magnesium is more negative than that of chromium, there is no reaction when a piece of chromium metal is dipped into a solution of Mg^2+.
Similarly, though metals displace hydrogen gas from dilute acids, metals that are less than hydrogen in the reactivity series cannot do that. This explains why there is no reaction when copper and silver are dipped into dilute acid solutions.
Reaction occurs when iron is dipped into a nickel solution because the reduction potential of Fe^2+ is far more negative than that of Ni^2+.
In the laboratory, a general chemistry student measured the pH of a 0.592 M aqueous solution of triethanolamine, C6H15O3N to be 10.781. Use the information she obtained to determine the Kb for this base.
Kb(experiment) =_______
Answer:
[tex]Kb=6.16x10^{-7}[/tex]
Explanation:
Hello,
In this case, given the pH of the base, we can compute the pOH as shown below:
[tex]pOH=14-pH=14-10.781=3.219[/tex]
Next, we compute the concentration of the hydroxyl ions when the triethanolamine is dissociated:
[tex]pOH=-log([OH^-])[/tex]
[tex][OH^-]=10^{-pOH}=10^{-3.219}=6.04x10^{-4}M[/tex]
Then, by writing the equilibrium expression for the dissociation of triethanolamine we have:
[tex]Kb=\frac{[OH^-][C6H14O2N^+]}{[C6H15O3N ]}[/tex]
That is suitable for the direct computation of Kb, knowing that based on the ICE procedure, [tex]x[/tex] equals the concentration of hydroxyl ions that was previously, computed, therefore, we have:
[tex]Kb=\frac{6.04x10^{-4}M*6.04x10^{-4}M}{0.592M-6.04x10^{-4}M}\\ \\Kb=6.16x10^{-7}[/tex]
Regards.
Calculate the missing variable. M1 = 4.0 M V1 = 450mL M2 = ? V2 = 800mL
Answer:7.1
Explanation:
m1=v1
m2=v2
let m2 be x
4.0=450
x=800
cross multiply
4.0 x 800=450x
3200=450x
x = 3200/450
x=m2=7.1
Enter your answer in the provided box. Before arc welding was developed, a displacement reaction involving aluminum and iron(III) oxide was commonly used to produce molten iron (the thermite process). This reaction was used, for example, to connect sections of iron railroad track. Calculate the mass of molten iron produced when 2.88 kg of aluminum reacts with 24.4 mol of iron(III) oxide.
Answer:
2.7255 kg Fe
Explanation:
Based on the reaction of the thermite process:
2 Al(s) + Fe₂O₃(s) → Al₂O₃(s) + 2 Fe(l)
2.88kg of Al (Molar mass: 26.98g/mol) are:
2880g ₓ (1mol / 26.98g) = 106.7 moles Al
For a complete reaction of these moles of Al are necessaries:
106.7 moles Al ₓ ( 1 mol Fe₂O₃ / 2 moles Al) = 53.35 moles Fe₂O₃
As you have just 24.4 moles of Fe₂O₃, Fe₂O₃ is limiting reactant.
1 mole of Fe₂O₃ produce 2 moles of Fe.
Thus, moles of Fe produced are 24.4×2 = 48.8 moles of Fe.
As molar mass of Fe is 55.85g/mol, mass of Fe is:
48.8 moles Fe ×(55.85g / mol) = 2725.5g of Fe =
2.7255 kg FeThe first solution will be an unbuffered sucrose solution. Calculate the amount of 0.1 M sucrose stock solution and the amount of dH2O needed to prepare 100 mL of unbuffered 20 mM sucrose.
Answer:
20mL of the stock solution and dilute to 100mL
Explanation:
20mM = 0.020M is the concentration of the diluted solution. As you want to prepare this solution from a 0.1M solution, dilution factor is:
0.1M / 0.020M = 5
That means you need to dilute the stock solution 5 times to obtain the 20mM sucrose solution.
As you want to prepare 100mL, you need to add:
100mL / 5 =
20mL of the stock solution and dilute to 100mLPre-Lab Study Questions / 9
1. Where are the valence electrons in an atom?
valen
2. How are positive and negative ions fomed?
3. Why are electrons shared in molecular compounds?
Answer:
See detailed answer with explanation below.
Explanation:
Valence electrons are electrons found on the outermost shell of an atom. They are the electrons in an atom that participate in chemical combination. Recall that the outermost shell of an atom is also referred to as its valence shell. Let us consider an example; if we look at the atom, sodium-11, its electronic configuration is 2,8,1. The last one electron is the valence electron of sodium which is found in its outermost or valence shell.
Positive ions are formed when electrons are lost from the valence shell of an atom. For instance, if the outermost electron in sodium is lost, we now form the sodium ion Na^+ which is a positive ion. Positive ions possess less number of electrons compared to their corresponding atoms.
Negative ions are formed when one or more electrons is added to the valence shell of an atom. A negative ion possesses more electrons than its corresponding atom. For example, chlorine(Cl) contains 17 electrons but the chloride ion (Cl^-) contains 18 electrons.
In molecular compounds, a bond is formed when two electrons are shared between the bonding atoms. Each bonding atom may contribute one of the shared electrons (ordinary covalent bond) or one of the bonding atoms may provide the both shared electrons (coordinate covalent bond). The shared pair may be located at an equidistant position to the nucleus of both atoms. Similarly, the electron may be drawn closer to the nucleus of one atom than the other (polar covalent bond) depending on the electro negativity of the two bonding atoms.
The electrons are shared in order to complete the octet of each atom by so doing, the both bonding atoms now obey the octet rule. For example, two chlorine atoms may come together to form a covalent bond in which each chlorine atom has an octet of electrons on its outermost shell.
Which metal will spontaneously react with Zn2+
(aq),
but will not spontaneously react with Mg2+
(aq)
according to the activity series
The options of the question is not given so the options are;
(1) Mn(s)
(2) Cu(s)
(3) Ni(s)
(4) Ba(s)
Answer: Mn(s)
Explanation:
The spontaneous reaction depends on the Eo value. The positive Eo value are spontaneous and the negative Eo values are not spontaneous.
so, here the Eo values are:
Eo Zn2+/Zn = -0.763v
Eo Mg2+/Mg = 2.37v
Eo Mn2+/Mn = -1.18v
Therefore, Eo cell (with Zn as one of the half-cell) = Eo Zn2+/Zn - Eo Mn2+/Mn
= -0.763 - (-1.18)
= 0.417v
Whereas, Eo cell (with Mg as one of the half-cell) = Eo Mg2+/Zn - Eo Mn2+/Mn
= -2.37 - (-1.18) = -1.19v
Thus, Mn(s) metal will spontaneously react because it has a positive Eo value and Zn2+(aq), but will not spontaneously react with Mg2+(aq) because it has negative Eo value.
In the first step of glycolysis, the given two reactions are coupled. reaction 1:reaction 2:glucose+Pi⟶glucose-6-phosphate+H2OATP+H2O⟶ADP+PiΔG=+13.8 kJ/molΔG=−30.5 kJ/mol Answer the four questions about the first step of glycolysis. Is reaction 1 spontaneous or nonspontaneous?
Answer: Reaction 1 is non spontaneous.
Explanation:
According to Gibb's equation:
[tex]\Delta G=\Delta H-T\Delta S[/tex]
[tex]\Delta G[/tex] = Gibbs free energy
[tex]\Delta H[/tex] = enthalpy change
[tex]\Delta S[/tex] = entropy change
T = temperature in Kelvin
When [tex]\Delta G[/tex] = +ve, reaction is non spontaneous
[tex]\Delta G[/tex]= -ve, reaction is spontaneous
[tex]\Delta G[/tex]= 0, reaction is in equilibrium
For the given reaction 1: [tex]glucose+Pi\rightarrow glucose-6-phosphate+H_2O[/tex] [tex]\Delta G=+13.8kJ/mol[/tex]
As for the reaction 1 , the value of Gibbs free energy is positive and thus the reaction 1 is non spontaneous.
QUESTION 11
Which of the following compounds has the highest boiling poid?
O CH3CH2CH2COOH
O CH3OCH2CH2CH3
O CH3CH2CH2OH
O CH3CH2CH2CHO
Answer:
CH3CH2CH2COOH
Explanation:
Both carboxylic acids and alcohols posses hydrogen bonding. The difference between the two lies in the strength of the hydrogen bonding and the structure of the molecules.
Alcohols predominantly form linear hydrogen bonds in which the dipole of the -OH group of one molecule interacts with that of another molecule. This gives a linear arrangement of hydrogen bonded intermolecular interactions which significantly impacts the boiling point of alcohols.
However, the carboxylic acids posses the carbonyl (C=O) which is more polar and interacts more effectively with the -OH bond to form dimmer species. These dimmers have a much higher boiling point than the corresponding alcohols due to stronger hydrogen bonds. Hence CH3CH2CH2COOH has a greater boiling point than CH3CH2CH2OH.
The other compounds in the options do not posses hydrogen bonds hence they will have much lower boiling points.
Consider the heating curve for water. A graph of the heating curve for water has time in minutes on the horizontal axis and Temperature in degrees Celsius on the vertical axis. A line runs through the following points: 0 minutes, negative 20 degrees; 0.5 minutes, 0 degrees; 2 minutes, 0 degrees; 4 minutes, 100 degrees; 8 minutes, 100 degrees; 9.5 minutes, 160 degrees. At what temperature does the solid start melting? –20°C 0°C 20°C 80°C
Answer:
0°C.
Explanation:
Hello,
In this case, given the heating curve of water on the attached document, we can notice that at 0 °C the solid starts melting, which means that the melting point is reached. Melting point is known as a physical change whereby a solid changes to liquid by the addition of heat as it allows the molecules to separate to each other.
Best regards.
Answer:
0 degrees celcius
Explanation:
I took the test
How does each of the following affect the solubility of an ionic compound: (a) Lattice energy Increasing solubility with increasing lattice energy. Lattice energy does not affect solubility. Decreasing solubility with increasing lattice energy. (b) Solvent (polar vs nonpolar) Ionic compounds are more soluble in a polar solvent. Solvent polarity does not affect solubility. Ionic compounds are more soluble in a nonpolar solvent. (c) Enthalpies of hydration of cation and anion Increasing solubility with increasing enthalpy of hydration. Enthalpy of hydration does not affect solubility. Decreasing solubility with increasing enthalpy of hydration.
Answer:
A) Decreasing solubility with increasing lattice energy.
B) Ionic compounds are more soluble in a polar solvent.
C) Increasing solubility with increasing enthalpy of hydration.
Explanation:
A) Lattice energy is the energy contained in the crystal lattice of a compound (mostly ionic). It is also the energy that would be released if the component ions were brought together from infinity to form the compound.
For a compound to dissolve, the solvation energy that the fluid would use to work on its ions must exceed the compound's lattice energy. Hence, the higher the lattice energy, the less soluble the compound would be.
B) The 'like dissolves like' law in dissolution is very true and applicable. The law explains that polar compounds will dissolve in polar solvents and not dissolve in non-polar solvents. Only non-polar compounds will dissolve in non-polar solvents.
Ionic compounds contain positive and negative ions, making them one of the most polar sets of compounds. So, they will easily dissolve in polar solvents.
C) Enthalpies of hydration of the cations and anions represent the total enthalpy of dissolution. This is the energy released when a compound undergoes hydration. A form of salvation of the ions, the enthalpy of hydration need to match or exceed the lattice energybof the compound For the compound to be soluble. Hence, the larger the enthalpies of hydration, the more likely the compound will be soluble.
Hope this Helps!!!