Answer:
3.46
Explanation:
Hello,
This question can be solved using Henderson-Hasselbalch equation.
The dissociation equation of acetic acid in water is
CH₃COOH + H₂O ⇄ CH₃COO⁻ + H₃O⁺
pH = pKa + log([conjugate base] / [weak acid])
Conjugate base = acetic acid
Weak acid = water
pKa = 4.76
pH = 4.76 + log([0.05]/[1])
pH = 4.76 + log(0.05)
pH = 4.76 + (-1.30)
pH = 3.46
From the above solution, the pH of the solution is 3.46
What is the mass of 3.45 moles
NO2?
(N = 14.01 g/mol, O = 16.00 g/mol)
Answer:
158.7 g
Its the right answer
if 2.22 moles of ammonia (NH3) decomposes according to the reaction shown how many moles of hydrogen (H2) are formed?
Answer:
five(5) hydrogen are formed
Dinitrogen tetraoxide, a colorless gas, exists in equilibrium with nitrogen dioxide, a reddish brown gas.
One way to represent this equilibrium is:
N2O4(g)----------> 2NO2(g)
<----------
Indicate whether each of the following statements is true or false
At equilibrium at a fixed temperature, we can say that:
1. The concentration of NO2 is equal to the concentration of N2O4.
2. The rate of dissociation of N2O4 is equal to the rate of formation of N2O4.
3. The rate constant for the forward reaction is equal to the rate constant of the reverse reaction.
4. The concentration of NO2 divided by the concentration of N2O4 is equal to the same constant (regardless of initial concentrations)
Explanation:
N2O4(g) <----------> 2NO2(g)
Before proceeding,
A chemical equilibrium can be defined as a condition in the course of a reversible chemical reaction in which no net change in the amounts of reactants and products occurs.
Statement 1.
This statement is false. Equilibrium is not about equal concentrations but rather zero change in concentration of the reactants and products.
Statement 2.
This statement is True in chemical equilibrium; the forward and reverse reactions occur at equal rates.
Statement 3.
This statement is False. The rate constant for the forward reaction is not equal to the rate constant of the reverse reaction.
Statement 4.
The concentration of NO2 divided by the concentration of N2O4 is NOT equal to a constant. To obtain a constant value irregardless of the concentrations, the concentration of NO2 must be squared. This comes from the stoichiometry of the reaction
Kc= [NO2]2 / [N2O4]
This statement is false.
What is ductility in a solid?
Answer:
Ductility is the how stretchable a solid is under tension. If a solid is ductile, then it can be stretched into wire-like (think rubber band). Ductility is similar to malleability and physical components of solids.
Explanation:
Why Graphite is Diamagnetic?
Answer: Through years of studying and research ;
Graphite has shown that in weak and quantizing magnetic fields it is material is a highly anisotropie diamagnetic substance whose non-oscillating part of the magnetic suscepti- bility weakly depends on magnetic field.
Explanation:
Diamagnetism is a (very) weak form of magnetism which is caused (induced) by a change in the orbital motion of electrons mostly due to an applied magnetic field.
A 0.580 g sample of a compound containing only carbon and hydrogen contains 0.480 g of carbon and 0.100 g of hydrogen. At STP, 33.6 mL of the gas has a mass of 0.087 g. What is the molecular (true) formula for the compound
Answer:
Molecular formula for the gas is: C₄H₁₀
Explanation:
Let's propose the Ideal Gases Law to determine the moles of gas, that contains 0.087 g
At STP → 1 atm and 273.15K
1 atm . 0.0336 L = n . 0.082 . 273.15 K
n = (1 atm . 0.0336 L) / (0.082 . 273.15 K)
n = 1.500 × 10⁻³ moles
Molar mass of gas = 0.087 g / 1.500 × 10⁻³ moles = 58 g/m
Now we propose rules of three:
If 0.580 g of gas has ____ 0.480 g of C _____ 0.100 g of C
58 g of gas (1mol) would have:
(58 g . 0.480) / 0.580 = 48 g of C
(58 g . 0.100) / 0.580 = 10 g of H
48 g of C / 12 g/mol = 4 mol
10 g of H / 1g/mol = 10 moles
The molecular formula of the compound is C4H10.
At STP;
P = 1 atm
T = 273 K
V = 33.6 mL or 0.0336 L
R = 0.082 atmLK-1mol-1
n = ?
Hence;
n = PV/RT
n = 1 atm × 0.0336 L/0.082 atmLK-1mol-1 × 273 K
n = 0.0015 moles
Number of moles = mass/molar mass
Molar mass= Mass/Number of moles
Molar mass = 0.087 g/0.0015 moles
Molar mass = 58 g/mol
Mass of carbon = (58 g × 0.480) / 0.580 = 48 g of C
Mass of hydrogen = (58 g × 0.100) / 0.580 = 10 g of H
Number of moles of carbon = 48 g of C / 12 g/mol = 4 mol
Number of moles of hydrogen = 10 g of H / 1g/mol = 10 moles
Formula of the compound must then be C4H10.
Learn more: https://brainly.com/question/2510654
chromate is sparingly soluble in aqueous solutions. The Ksp of Ag2CrO4 is 1.12×10−12 . What is the solubility (in mol/L) of silver chromate in 1.00 M potassium chromate aqueous solution?
Answer:
[tex]6.5X10^-^5~\frac{mol}{L}[/tex]
Explanation:
For this question, we have to start with the ionization equation for [tex]Ag_2CrO_4_(_s_)[/tex], so:
[tex]Ag_2CrO_4_(_s_)~<->~2Ag^+~_(_a_q_)~+~CrO_4^-^2_(_a_q_)[/tex]
With this in mind we can write the Ksp expression:
[tex]Kps~=~[Ag^+]^2[CrO_4^-^2][/tex]
Additionally, for every mole of [tex]CrO_4^-^2[/tex] formed, 2 moles of [tex]Ag^+[/tex] are formed. We can use "X" for the unknown concentration of each ion, so:
[tex][CrO_4^-^2]~=~X[/tex] and [tex][Ag^+]~=~2X[/tex]
Now, we can plug the values into the Ksp expression:
[tex]1.12x10^-^1^2~=~(2X)^2(X)[/tex]
Now we can solve for "X" :
[tex]1.12x10^-^1^2~=~4X^3[/tex]
[tex]X^3=\frac{1.12X10^-^1^2~}{4}[/tex]
[tex]X=(\frac{1.12X10^-^1^2~}{4})^(^1^/^3^)[/tex]
[tex]X=6.5X10^-^5~\frac{mol}{L}[/tex]
I hope it helps!
Based on the type or types of intermolecular forces, predict the substance in each pair that has the higher boiling point Given the molecules propane (C3H8) and n-butane (C4H10)_________ has the higher boiling point mainly due to_______ Given the molecules diethyl ether (CH3 CH2OCH2 CH3) and 1-butanol (CH3 CH2CH2 CH2OH) higher boiling point mainly due to______________ .
Answer:
See explanation
Explanation:
-) Given the molecules propane (C3H8) and n-butane (C4H10) n-butane has the higher boiling point mainly due to a larger chain of carbons.
In this question, in propane, we have a chain of three carbons. In butane, we have fourth carbons. If we have more carbons we will have more interactions. If we have more interactions we have to give more energy to go from liquid to gas, therefore we will have a higher boiling point.
-) Given the molecules diethyl ether (CH3 CH2OCH2 CH3) and 1-butanol (CH3 CH2CH2 CH2OH) 1-butanol has a higher boiling point mainly due to hydrogen bonding.
In the case of butanol, we have the "OH" group. If we have a hydrogen bond to a heteroatom (O, S, P, or N) we will have the presence of this type of interaction between molecules. If we have more interactions we have to give more energy to go from liquid to gas, therefore we will have a higher boiling point.
I hope it helps!
At what geographical location would the boiling point of water be lowest?
A. Boston, Massachusetts
B. The coast of the Atlantic Ocean
C. The Dead Sea
D. The top of Mount Everest
Answer:
I think it would be the Dead Sea
Explanation:
Because the dead sea is already usually in the warmer temperatures, the boiling point of the water would be lower than the rest.
what is the molarity of a solution that contains 49.8 grams of nai and is dissolved in enough water to make 1.50 liters
Answer: The molarity of solution is 0.221 M
Explanation:
Molarity of a solution is defined as the number of moles of solute dissolved per liter of the solution.
[tex]Molarity=\frac{n}{V_s}[/tex]
where,
n = moles of solute
[tex]V_s[/tex] = volume of solution in L
moles of [tex]NaI[/tex] = [tex]\frac{\text {given mass}}{\text {Molar mass}}=\frac{49.8g}{149.89g/mol}=0.332mol[/tex]
Now put all the given values in the formula of molality, we get
[tex]Molarity=\frac{0.332mol}{1.50L}[/tex]
[tex]Molarity=0.221mol/L[/tex]
Therefore, the molarity of solution is 0.221 M
Which element has the largest atomic radius
Answer:
Francium
Explanation:
The atomic radius increases from top to bottom in a group, and decreases from left to right across a period.
so francium (Fr) is the largest atom or has highest radii.
Hope this helps & please mark as brainiest!
Answer:
Francium has the largest atomic radius.
The general trend for atomic radii is increasing from top to bottom and decreasing from left to right so the one with the largest atomic radius will be in the bottom left of the periodic table.
Draw the structure of the organic product(s) of the Grignard reaction between dimethyl carbonate (CH3OCO2CH3) and excess phenylmagnesium bromide, followed by aqueous workup. You do not have to consider stereochemistry. If a compound is formed more than once, add another sketcher and draw it again. Alternatively, you may use the square brackets tool to add stoichiometries greater than one. Draw one structure per sketcher. Add additional sketchers using the dropdown menu in the bottom right corner. Separate multiple products using the + sign from the dropdown menu.
Answer:
dimethoxy(phenyl)methanol
Explanation:
For this question, we have to remember the mechanism of the Grignard reaction. In this case, phenylmagnesium bromide is our nucleophile, a carbo-anion is produced (step 1). Then this carbo-anion can attack the carbonyl group in the dimethyl carbonate, the double bond is delocalized into the oxygen producing a negative charge (step 2). Finally, with the addition of the hydronium ion ([tex]H_3O^+[/tex]), the anion can be protonated to produce the alcohol (dimethoxy(phenyl)methanol) (step 3).
See figure 1
I hope it helps!
when dissolved in water, an acid or a base breaks down into a. a proton and an electron b. two negative ions c. a positive and a negative ion d. a positive ion and a proton
Answer:
C. A positive and a negative ion
Explanation:
Acids and bases are made up of charged particles known as ions. The ions present in acids are oppositely charged and are held together by strong electrostatic forces. When acids or bases are dissolved in water, the electrostatic forces holding their individual molecules together are weakened and these ions are free to move apart in a process known as dissociation. Dissociation occurs because of the attraction between the positive and negative ions in the acid and bases and the negative and positive polarity of water.
For example, when an acid like hydrochloric acid is dissolved in water it dissociates into positive and negative ions as follows:
HCl(aq) -----> H+ + Cl-
When a base like sodium hydroxide is dissolved in water, it dissociates into positive and negative ions as follows:
NaOH(aq) ----> Na+ + OH-
Answer:
yeah C is correct
Explanation:
Consider 2H2 + O2 → 2H2O. To produce 1.2 g water, how many grams of H2 are required? Report to the correct number of significant figures. Show work for full credit!
Answer:
0.133 mol (corrected to 3 sig.fig)
Explanation:
Take the atomic mass of H=1.0, and O=16.0,
no. of moles = mass / molar mass
so no. of moles of H2O produced = 1.2 / (1.0x2+16.0)
= 0.0666666 mol
From the equation, the mole ratio of H2:H2O = 2:2 = 1:1,
meaning every 1 mole of H2 reacted gives out 1 mole of water.
So, the no, of moles of H2 required should equal to the no, of moles of H2O produced, which is also 0.0666666 moles.
mass = no. of moles x molar mass
hence,
mass of H2 required = 0.066666666 x (1.0x2)
= 0.133 mol (corrected to 3 sig.fig)
What is the effect on the concentration of hydrofluoric acid, hydronium ion, and fluoride ion when the following are added to separate solutions of hydrofluoric acid? (a) HCl (b) KF (c) NaCl (d) KOH (e) HF
Answer:
Whenever a system in equilibrium gets disturbed, the adjustment of the system is done in such a manner that the effect of the change gets nullified, this is known as Le Chatelier's Principle. Let us consider that if a reaction present in an equilibrium gets disturbed by changing pressure, concentration, pressure, or other things, then the reaction will move in such a manner so that it can attain the equilibrium again.
Based on the given question, the equation is:
HF (aq) + H2O (l) ⇒ H3O+ (aq) + F- (aq)
a) When HCl is added, the dissociation of HCl takes place within the water to give rise to Cl- and H3O+ ions. One can witness an overall enhancement in the H3O+ ions concentration and the shifting of the equilibrium will take place in the backward direction based on the Le-Chatelier's principle. Thus, on adding HCl, the concentration of H3O+ and F- ions decreases, and the concentration of HF increases.
b) When the addition of a strong electrolyte like KF is done, the dissociation of KF is done into the F- and K+ ions. Thus, with the overall enhancement in the F- ions concentration, the shifting of equilibrium will take place in the backward direction based on the Le-Chatelier's principle. Thus, with the addition of KF, the concentration of H3O+ and F- ions decreases, and HF increases.
c) With the addition of strong electrolytes like NaCl in the solution, the dissociation of NaCl takes place into the Cl- and Na+ ions. With the addition of NaCl, the equilibrium is not disturbed as the ions exhibit no influence on the given equilibrium reaction. Thus, the concentration of H3O+, HF, and F- ions remains unmodified.
d) With the addition of KOH, the dissociation of KOH takes place into K+ and OH- ions. Based on Le-Chatelier's principle, the equilibrium will shift in the forward direction as the produced OH- ions will consume the hydronium ions. Therefore, the concentration of H3O+ and F- ions increases, while the concentration of HF decreases.
e) With the addition of HF, that is, a weak acid, the equilibrium will move in the forward direction to counter the change as the concentration of reactant increases. Therefore, the H3O+ and F- ions decreases, and the concentration of HF increases.
On adding HCl & KOH to the equilibrium concentration of hydronium ion changes, on adding KF concentration of fluoride ion changes, on adding NaCl no change occur and on adding HF concentration of both ion increases.
What is equilibrium law?According to the equilibrium law whenever any stress is applied at the equilbrium state of chemical reaction, then the equilibrium will move on that direction where the effect of the applied stress will decreases.
Given chemical reaction is:
HF (aq) + H₂O (l) ⇄ H₃O⁺ (aq) + F⁻ (aq)
If in the reaction HCl is added then it increases the concentration of H₃O⁺ as HCl will dissociate into H⁺ ion and Cl⁻ ion, so the equilibrium will shift towards the left side to maintain the concentration of H₃O⁺ ion.If KF is added in the reaction then it increases the concentration of F⁻ ion as HF will dissociates into H⁺ ion and F⁻ ion, so the equilibrium will shift towards the left side to maintain the concentration of F⁻ ion.On adding NaCl there is no change in the equilibrium as its dissociation doesn't change any concentration of the reaction.On adding KOH equilibrium will shift towards the right side, as the produced hydroxide ion will consume the hydronium ion to produce water.On adding HF reaction will move towards the right side to maintain the concentration of reactant.Hence affect on the equilibrium was discussed above.
To know more about equilibrium law, visit the below link:
https://brainly.com/question/2943338
(-)-Cholesterol has a specific rotation of -32o. A mixture of ( )- and (-)-cholesterol was analyzed by polarimetry, and the observed rotation was 14o. What is the percent composition of the ( ) isomer in this mixture
Answer:
(+)-cholesterol = 71.88%
(-)-cholesterol = 28.12%
Explanation:
Asuming 1 gram of sample is dissolved in 1mL of water and the sample cell was 1dm long.
Enantiomeric excess is defined as the amount of pure enantiomer in a sample. The formula is:
ee = [α]mixture / [α]pure enantiomer.
Replacing:
ee = 14° / 32°×100 = 43.75%
As the sample is 14°, There is an excess of (+)-cholesterol and 56.25% is a 1:1 mixture of enantiomers.
That means percent composition of enantiomers is:
(+)-cholesterol = 43.75% + 56.25%/2 = 71.88%(-)-cholesterol = 56.25%/2 = 28.12%A small amount of red paint is mixed with water. When a laser pointer shines through the mixture, the beam is clearly visible in the mixture. This mixture is a .
Answer: Heterogeneous (Colloid)
Explanation: This is because your solution is a colloid. A colloidal solution has particles between 40 and 900 nm and as the laser light shines through the paint and Water mixture, the paint particles scatter the light because of the Tyndall Effect (Named after the physicist John Tyndall). A Colloidal Solution is a heterogeneous solution that looks like its homogeneous but is a mixture of very small particles that don't really become a solution.
A small amount of red paint is mixed with water. When a laser pointer shines through the mixture, the beam is clearly visible in the mixture. This mixture is a Heterogeneous.
What is mixture?A mixture is a substance made by combining two or more dissimilar chemical compounds that are not chemically linked in chemistry. When two or more substances are physically combined, their identities are maintained, and the mixture takes the shape of solutions, suspensions, or colloids.
Chemical elements and compounds, among others, can be mechanically blended or mixed to create mixtures without causing any chemical bonding and other chemical change, preserving the chemical characteristics and makeup of each ingredient. A small amount of red paint is mixed with water. When a laser pointer shines through the mixture, the beam is clearly visible in the mixture. This mixture is a Heterogeneous.
Therefore, the mixture is Heterogeneous mixture.
To know more about mixture, here:
https://brainly.com/question/12160179
#SPJ2
Select all the true statements regarding chemical equilibrium.
At equilibrium...
A. the concentrations of reactants and products are equal.
B. the concentrations of reactants and products remain constant.
C. reactants are still being converted to products (and vice versa).
D. the rates of the forward and reverse reactions are equal.
Answer:
Choice B, C, and D.
Explanation:
Choice A is not true in general. Here's a way to think about that. Consider a very special equilibrium where the concentration of reactants and products are indeed equal. When one of the external factors (such as temperature) changes, the equilibrium will shift towards either side of the reaction. More products will be converted to reactants, or vice versa. Either way, in the new equilibrium, the concentration of the reactants and products will not be equal any more.
Choice B should be considered with choice C and D in mind.
Choice C is indeed correct. The reaction rate would not be zero unless all the reactants were used up or taken out of the system. That's not what happens in an equilibrium. Instead, when reaction rate is plotted against time, the graph for reactions in both directions will eventually flat out at a non-zero value.
Choice D explains why even though choice C is correct, the concentration of a system at equilibrium stays the same. At the equilibrium, reactions in both directions are still happening. However, during the time it takes for the forward reaction use up some reactant particles, the reverse reaction would have produced these particles again. On a large scale, there would be no observable change to the concentration of each species in the equilibrium. Therefore, choice B is also correct.
which factor is most responsible for the fact that water is a liquid rather than a gas at room temperature
The answer is Hydrogyn bonding. It keeps the water molocules bonded together and in a liquid state, without it it'd be in a gashious state.
Answer:Hydrogen bonds keep them together in room temperature, hope this helps!
Explanation:
<!> Brainliest is appreciated! <!>
A student wants to make a 0.250 M aqueous solution of silver nitrate, AgNO3, and has a bottle containing 15.89 g of silver nitrate. What should be the final volume of the solution? When you give your numerical answer, what is the correct significant figures and how do you know that is the correct amount?
Answer:
0.374 L
Explanation:
Step 1: Given data
Mass of silver nitrate (solute): 15.89 g
Molarity of the solution: 0.250 M
Step 2: Calculate the moles of silver nitrate
The molar mass of silver nitrate is 169.87 g/mol.
[tex]15.89g \times \frac{1mol}{169.87g} = 0.09354mol[/tex]
Step 3: Calculate the volume of the solution
The molarity is equal to the moles of solute divided by the liters of solution.
[tex]M = \frac{moles\ of\ solute }{volume\ of\ solution} \\volume\ of\ solution = \frac{moles\ of\ solute}{M} = \frac{0.09354mol}{0250mol/L} = 0.374 L[/tex]
Due to the significant figures rules, we keep 3 significant figures.
Answer:
0.37416 L
Explanation:
M = mol/L
molar mass ( for AgNO₃ ) = 169.87 g
moles = given mass/molar mass
15.89 g/169.87 = .09354
.250 = .09354/L
= 0.37416
Identify which of the following are carbohydrates.
Check oh that apply
Answer:
3d and 4th
Explanation:
Carbohydrates general formula (CH2O)n.
Not 1st one because it has NH2-group.
2nd - C3H6O4, also it is acid.
3d - C3H6O3
4th - C6H12O6
Among the given compounds only compound present in 3rd option is a carbohydrate.
What are carbohydrates?Carbohydrates are the organic molecules which are made up of oxygen atom, carbon atom and hydrogen atom and general molecular formula of carbohydrates is CₙH₂ₙOₙ, where n is the number of atoms.
In the carbohydrate molecule, alcoholic group and aldehyde groups may present.
First given compound is not a carbohydrates as in that NH₃ group is present.Second given compound is also not a carbohydrate as in that carboxylic (-COOH) group is present.Third compound is a carbohydrate as in that compound same number of carbon and oxygen atoms are present and number of hydrogen atom is double to C & O atom.Fourth compound is also not a carbohydrate, as in that molecule number of carbon and oxygen atom is same but number of hydrogen is not double with respect to C & O.Hence compound C is carbohydrate.
To know more about carbohydrates, visit the below link:
https://brainly.com/question/26200989
A student wants to prepare a salt starting with H2SO4. Select all of the compound types that can react with H2SO4 to form a salt.
1. salt
2. acid
3. acid salt
4. basic oxide
5. base
6. metal
7. acidic oxide
Answer:
4 and 6 would work for this
1 C8H10(l) +21/2O2(g) → 8CO2(g) + 5H2O(g), Hcomb= ? Hf for C8H10(l) = +49.0kJ/mol C8H10(l) Use the balanced combustion reaction above to calculate the enthalpy of combustion (Hcomb) for C8H10
Answer:
[tex]H_{comb}=-4406kJ/mol[/tex]
Explanation:
Hello,
In this case, the enthalpy of combustion is understood as the energy released when one mole of fuel, in this case octene, is burned in the presence of oxygen and is computed with the enthalpies of formation of the fuel, carbon dioxide and water as shown below (oxygen is circumvented as it is a pure element):
[tex]H_{comb}=8*\Delta _fH_{CO_2}+5\Delta _fH_{H_2O}-\Delta _fH_{C_8H_{10}}[/tex]
Thus, since we already know the enthalpy of combustion of the fuel, for carbon and water we have -393.5 and -241.8 kJ/mol respectively, thereby, the enthalpy of combustion turns out:
[tex]H_{comb}=8*(-393.5kJ/mol)+5(-241.8kJ/mol)-49.0kJ/mol\\\\H_{comb}=-4406kJ/mol[/tex]
Best regards.
1-chloro-4-methyl-2-pentene undergoes hydrolysis in warm water to give a mixture of 4-methyl-2-penten-1-ol and 4-methyl-1-penten-3-ol. Draw the structure of the intermediate's resonance contributor leading to the formation of 4-methyl-1-penten-3-ol.
Answer:
Explanation:
attached here is the diagram representing the structure
In the reaction C+02 arrow C02 which element is reduced in the reaction? C O2 CO2
Answer:
O2
Explanation:
Answer:
o2
Explanation:
edge
What is the pressure of 5.0 Mol nitrogen (N2) gas in a 2.0 L container at 268 K?
Answer:
pressure is = 54.9802atm
Explanation:
using ideal gas equation
PV=nRT
Hypothesis 1: If you increase the
temperature of a reaction, then the reaction
rate will increase because particles experience
more collisions at higher temperatures.
To test the first hypothesis, you measured the
reaction rate for several different?
volumes.
temperatures.
densities.
particle sires.
Answer:is increase and more collisions :)
Explanation:
Write the empirical formula
Answer:
[tex]1) NH_{4}IO_{3}\\2) Pb(IO_{3})_{4} \\3) NH_{4}(C_{2}H_{3}O_{2})\\4) Pb(C_{2}H_{3}O_{2})_{4}[/tex]
Explanation:
[tex]1) NH_{4}^{+}IO_{3}^{-} ---> NH_{4}IO_{3}\\2) Pb^{4+}(IO_{3}^{-})_{4} --->Pb(IO_{3})_{4} \\3) NH_{4}^{+}(C_{2}H_{3}O_{2})^{-} ---> NH_{4}(C_{2}H_{3}O_{2})\\4) Pb^{4+}(C_{2}H_{3}O_{2})^{-} _{4} --->Pb(C_{2}H_{3}O_{2})_{4}[/tex]
What is the half-life for the first order decay of 14C according to the reaction, 146C — 147N +e- ?
The rate constant for the decay is 1.21 x10-4 year-1
Answer:
5727 years or 5730 (rounded to match 3 sig figs) whichever one your teacher prefers
Explanation:
First Order decay has a half life formula of Half Life = Ln (2) / k = 0.693/K
Half-life = 0.693/k = 0.693/1.21 x10-4 = 5727 years or 5730 (rounded to match 3 sig figs)
This should be correct because if you google the half-life of 14 C it is ~ 5700 years
A chemist measures the energy change Delta H during the following
2Fe2O3(s)->4FeO(s)+O2(g).
1) this reactions is: Endothermic or exothermic.
2) suppose 94.2g of Fe2O3 react. will any heat be relased or absorbed. yes absorbed. yes releases. no.
3) If you said heat will be released or absorbed in the second part of the question. calculate how much heat will be absored or released. be sure your answer has correct number of significant digits.
Answer: 1) Endothermic
2) Yes, absorbed.
3) 166.86 kJ will be absorbed.
Explanation:
1) To determine if a reaction is endothermic (heat is absorbed by the system) or exothermic (heat is released by the system), first calculate its change in Enthalpy, which is given by:
ΔH = [tex]H_{products} - H_{reagents}[/tex]
For the reaction 2Fe₂O₃(s) ⇒ 4FeO(s) + O₂(g):
Enthalpy of Reagent (Fe₂O₃(s))
Enthalpy of formation for Fe₂O₃(s) is - 822.2 kJ/mol
The reaction needs 2 mols of the molecule, so:
H = 2(-822.2)
H = - 1644.4
Enthalpy of Products (4FeO(s) + O₂(g))
Enthalpy of formation of O₂ is 0, because it is in its standard state.
Enthalpy of formation of FeO is - 272.04 kJ/mol
The reaction produces 4 mols of iron oxide, so:
H = 4(-272.04)
H = -1088.16
Change in Enthalpy:
ΔH = [tex]H_{products} - H_{reagents}[/tex]
ΔH = - 1088.16 - (-1644.4)
ΔH = + 556.2 kJ/mol
The change in enthalpy is positive, which means that the reaction is absorving heat. Then, the chemical reaction is Endothermic.
2) When Fe₂O₃(s) reacts, heat is absorbed because it is an endothermic reaction.
3) Calculate how many mols there is in 94.2 g of Fe₂O₃(s):
n = [tex]\frac{mass}{molar mass}[/tex]
n = [tex]\frac{94.2}{160}[/tex]
n = 0.6 mols
In the reaction, for 2 mols of Fe₂O₃(s), 556.2 kJ are absorbed. Then:
2 mols --------------- 556.2 kJ
0.6 mols ------------- x
x = [tex]\frac{0.6*556.2}{2}[/tex]
x = 167 kJ
It will be absorbed 167 kJ of energy, when 94.2 g of Fe₂O₃(s) reacts.