Answer:
d. 7.7x10^23 molecules
Explanation:
Given the following data:
Mass of water (H2O) = 23g
To find the number of molecules;
First of all, we would determine the number of moles;
[tex] Number \; of \; moles = \frac {mass}{molar mass} [/tex]
Molar mass of water (H2O) = (1 * 2) + 16 = 18 g/mol
Substituting into the equation, we have
[tex] Number \; of \; moles = \frac {23}{18} [/tex]
Number of moles = 1.2778 moles
Now, to find the number of water molecules;
We know that Avogadro constant is equal to 6.02 * 10^23 mol¯¹
Number of water molecules = number of H2O moles * Avogadro constant
Substituting into the equation, we have;
Number of water molecules = 1.2778 × 6.02 * 10^23
Number of water molecules = 7.7 × 10^23 atoms.
3
A student has a 5.00 gram sample of calcium chloride (CaCl2) solid. How many moles of calcium chloride are
contained in this sample?
Answer: 0.0450 moles of [tex]CaCl_2[/tex]
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to its molecular mass and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.
To calculate the moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}[/tex]
[tex]\text{Number of moles of} CaCl_2=\frac{5.00g}{110.98g/mol}=0.0450moles[/tex]
Thus there are 0.0450 moles of [tex]CaCl_2[/tex]
Mass number 107 and 61 neutrons
H.w. balance the following equations:
a) Iron + chlorine → Iron (iii) chloride
b) Nitrogen + hydrogen → Ammonia
c) Phosphoric acid + sodium carbonate → sodium phosphate + water + carbon dioxide
d) Nitrogen dioxide + water + oxygen → Nitric acid
Answer:
3iron + chlorine=iron3 chloride
nitrogen +3hydrogen
Answer:
a) Iron + chlorine → Iron (iii) chloride
3fe+cl__fe3cl
b) Nitrogen + hydrogen → Ammonia
2N+3h2------2NH3
c) Phosphoric acid + sodium carbonate → sodium phosphate + water + carbon dioxide
2H3PO3+3Na2CO3-----2Na3PO4+3H2O+3CO2
d) Nitrogen dioxide + water + oxygen → Nitric acid
NO2+H2O+O2--NOH
sorry if mistake
How can we solve food insecurity while reducing food waste?
o inventory food supplies to avoid overbuying
O donate unused food to food banks
O purchase only as much food as you need
O don't throw scraps in the landfill
Answer:
donate unused food to food banks
Explanation:
Becuse food banks processes food to make very fine particles which is mixed with soil and can be given to the plants
Why is it necessary to run TLC in a closed container and to have the interior vapor saturated with the solvent? What error is introduced into the determination of an Rf value if the top is left off of the developing chamber?
Answer:
See explanation
Explanation:
Rf value is known as retention factor.The retention factor of a particular material is the ratio of the distance the spot moved above the origin to the distance the solvent front moved above the origin(Harper College).
TLC is carried is out in a closed container and the interior is saturated with the solvent vapor in order to have a maximum resolution between components this prevents solvent from evaporating from the system.
Peradventure the solvent for the separation is partly or wholly lost due to an open container, the Rf value would be lower than the expected value.
A 52.9g sample of brass, which has a specific heat capacity of 0.375·J·g^−1°C^−1, is put into a calorimeter (see sketch at right) that contains 100.0g of water. The temperature of the water starts off at 15.0°C. When the temperature of the water stops changing it's 18.4°C. The pressure remains constant at 1 atm. Calculate the initial temperature of the brass sample.
Answer: 90.04°C
Explanation: Calorimeter is a device measures the amount of heat of a chemical or physical process. An ideal calorimeter is one that is well-insulated, i.e., prevent the transfer of heat between the calorimeter and its surroundings. So, the net heat change inside the calorimeter is zero:
[tex]q_{1}+q_{2}=0[/tex]
Rearraging, it can be written as
[tex]q_{1}=-q_{2}[/tex]
showing that the heat gained by Substance 1 is equal to the energy lost by Substance 2.
In our case, water is gaining heat, because its temperature has risen and so, brass is losing energy:
[tex]q_{water}=-q_{brass}[/tex]
Calculating:
[tex]m_{w}.c_{w}.\Delta T=-[m_{b}.c_{b}.\Delta T][/tex]
[tex]100.4.18.(18.4-15)=-[52.9.0.375.(18.4-T)][/tex]
Note: final temperature is the same as the substances are in thermal equilibrium.
Solving:
418(3.4)= - 365.01 + 19.8375T
19.8375T = 1786.21
T = 90.04
The initial temperature for the sample of brass was 90.04°.
Explain the flow of energy needed to bring electrical energy to the city.
Answer:
The electricity that flows to our homes is generated in the power station from here it flows through large transmission line which carry it to substations finally distribution carry electricity from substations to homes schools etc
Read: https://kids.britannica.com/kids/article/DNA/390730 (Links to an external site.)
Answer the following questions:
1. What sort of things does DNA determine for a creature? (Think physical traits)
2. Sometimes there are mistakes in DNA, what are these mistakes called? what sort of things can these mistakes cause?
3. What makes up the sides of the DNA structure?
4. There are four different bases in DNA: adenine, thymine, guanine, and cytosine. About how many total pairs do humans have in their DNA?
Answer:
im not doing your whole homework. but ill give you one cent ;>, whats ur paypal
Explanation:
Number of moles In 52.3 g of C12H22O11
Answer:
0.1529mol
Explanation:
Number of mole = x mol
Mass = 52.3g
Molar Mass of Sucrose
(C = 12, H = 1, O = 16)
C12H22O11
(12×12)+(1×22)+(16×11)
144 + 22 + 176
342g/mol
Number of Mole = Mass given/Molar mass
Number of mole = 52.3/342
Number of mole = 0.1529mol
50 POINTS
Which of the following correctly describes a compound?
A. The atoms are bonded together, and the compound has different physical and chemical properties than the individual elements.
B. The atoms have no set ratio for how the atoms can combine, and they are not chemically bonded together.
C. The atoms can only combine in fixed ratios, and they retain their individual chemical and physical properties.
D. The atoms retain their individual chemical properties, and they can only be separated from each other by a chemical change.
Answer: A chemical compound can be described as substance composed of atoms from more than one element held together by chemical bonds in a fixed stoichiometric proportion. A compound has different physical and chemical properties from its constituent elements.
For example : compound water is made up of H and O bonded together and it has different properties from O and H.
Thus, among the given options, the one coreectly describing a compound is
a) The atoms are bonded together, and the compound has different physical and chemical properties than the individual elements.
What is the half life of the graphed material?
Answer:
3 hours
Explanation:
To know the the correct answer to the question given above, it is important we know the definition of half-life.
The half-life of a substance is simply defined as the time taken for half the substance to decay.
Considering the diagram given above, the initial mass of the substance is 100 g.
Half of the initial mass = 100 / 2 = 50 g
Now, we shall determine the time from the graph taken to get to 50 g.
Considering the diagram given above, the time taken to get to 50 g is 3 hours.
Therefore, the half-life of the material is 3 hours.
On the basis of the information above, a buffer with a pH = 9 can best be made by using
A pure NaH2PO4
B H3PO4 + H2PO4–
C H2PO4– + PO42–
D H2PO4– + HPO42–
E HPO42– + PO43
Answer:
D H2PO4– + HPO42–
Explanation:
The acid dissociation constant for [tex]\mathbf{H_3PO_4 , H_2PO^{-}_4 , HPO_4^{2-}}[/tex] are [tex]\mathbf{7\times 10^{-3}, \ \ 8\times 10^{-8} ,\ \ 5\times 10^{-13}}[/tex] respectively.
[tex]\mathbf{pka (H_3PO_4) = -log (7\times 10^{-3} )=2.2}[/tex]
[tex]\mathbf{pka (H_2PO_4^-) = -log (8\times 10^{-8} )=7.1}[/tex]
[tex]\mathbf{pka (HPO_4^{2-}) = -log (5\times 10^{-13} )=12.3}[/tex]
The reason while option D is the best answer is that, the value of pKa for both
[tex]\mathbf{H_2PO^{-}_4 ,\ \& \ HPO_4^{2-}}[/tex] lies on either side of the desired pH of the buffer. This implies that one is slightly over and the other is slightly under.
Using Henderson-Hasselbach equation:
[tex]\mathbf{pH = pKa + log \Big( \dfrac{HPO_4^{2-}}{H_2PO_4^-} \Big)}[/tex]
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex]. Thus, option D is correct.
The buffers are the solutions of acids and base of appropriate pH, that are able to limit the change in pH in the reaction mixture.
Which compound is used for pH 9 buffer?The buffer pH is adjusted with the compounds that has been able to add base or acid to the solution.
For the formulation of buffer of specific pH, the acid and base solutions are required.
The compounds that are used for the formulation of the pH 9 buffer are [tex]\rm H_2PO_4^-\;and\;HPO_4^+[/tex], as they are able to provide acid and base to the solution.
Thus, option D is correct.
Learn more about buffers, here:
https://brainly.com/question/1423164
When the number of molecules, atoms, or ions of a particular type (here we consider H ions) is in the hundreds of millions, we can confidently speak of concentrations and analyze an average behavior.
a. True
b. False
Answer:
True.
Explanation:
When the number of molecules, atoms or ions of any element is in the hundreds of millions, we can safely speak of concentrations and analyze a standard behavior, and can even specify the different dilutions used, if there are dilutions. This allows analyzes to be clearly understood by any individual. However, it is not possible to do this if the number of molecules, atoms and ions is very small.
Can you think of an example where hydrogen and oxygen combine and release energy with little or no release of heat energy?
When hydrogen and oxygen combine, they form water or hydrogen peroxide, and energy is released in the process.
What are oxygen and hydrogen?
Oxygen and hydrogen are the chemical elements of the periodic table, and they both are gas. Oxygen is the most important gas, which is needed for breathing. It is present at 21% in the atmosphere.
Hydrogen is another gas present in nature. It is the lightest gas, and it has diatomic molecules. It remains gas at normal pressure and temperature, but it becomes liquid at low temperature.
The oxygen and hydrogen readily react and for water, and hydrogen peroxide, the process of reaction of hydrogen and oxygen releases an amount of energy.
Hence, Energy is released during the creation of water or hydrogen peroxide when hydrogen and oxygen mix.
Learn more about oxygen and hydrogen, here:
https://brainly.com/question/11556976
#SPJ5
the ph of a naoh solution is 12.05. what is the concentration of [oh-] of the naoh solution? express your answer in standard notation
Answer:
0.01 M
Explanation:
NaOH (sodium hydroxide) is a strong base, so it is completely dissociated into ions in aqueous solution:
NaOH ⇄ Na⁺ + OH⁻
So, we have OH⁻ ions in solution.
From the problem, we have the pH value. The pH is calculated as:
pH = -log [H⁺]
As NaOH is a base, we can also calculate the pOH:
pOH = -log [OH⁻]
Thus. we can use the relation between pH and pOH to calculate the pOH and then use it to calculate [OH⁻]:
pH + pOH = 14 ⇒ pOH = 14 - pH = 14 - 12.05 = 1.95
pOH = -log [OH⁻] ⇒ [OH⁻] = [tex]10^{-pOH}[/tex]= [tex]10^{1.95}[/tex]= 0.0112 M ≅ 0.01 M
Answer:
0.0112
Explanation:
They said that was the answer.
MnO4 - is a stronger oxidizing agent than ReO4 - . Both ions have charge-transfer (LMCT) bands; however, the charge-transfer band for ReO4 - is in the ultraviolet, whereas the corresponding band for MnO4 - is responsible for its intensely purple color. Are the relative positions of the charge-transfer absorptions consistent with the oxidizing abilities of these ions? Explain
Answer:
[tex]$MnO^-_4$[/tex] is a strong oxidizing agent.
Explanation:
The 5d orbitals of Re are higher in energy than 3 d orbitals of Mn. So an LMCT ligand to metal charge transfer excitation requires more energy of [tex]$ReO^-_4$[/tex].
Also, since the molecular orbitals are derived primarily from 3d orbitals of [tex]$MnO^-_4$[/tex] are lower in energy than the corresponding MO's of [tex]$ReO^-_4$[/tex], [tex]$MnO^-_4$[/tex] is better able to accept the electrons.
So it is a better oxidizing agent.
The ligand to metal charge transfer band in ReO4- occurs in the near UV region hence ReO4 - appears colorless.
The electron configuration of Re is Xe 4f14 5d5 6s2 and the electron configuration of Mn is [Ar] 3d5 4s2. We can see that Mn^7+ and Re^7+ have empty d orbitals.
The color of MnO4 - must result from ligand to metal charge transfer hence the purple color of MnO4 -. In the case of ReO4 -, the ligand to metal charge transfer occurs at a much higher energy owing to the fact that 5d orbitals are involved. This transition occurs in the near UV region hence ReO4 - appears colorless. The ligand to metal charge transfer in MnO4- involves lower energy 3d orbitals hence it occurs in the visible region of the spectrum.
Learn more: https://brainly.com/question/8646601
Is anyone good at 10th grade chemistry if so can someone help me please ?
If I have 5 moles of a gas at a pressure of 6.5 atm and a volume of 14 liters, what is the temperature?
PV=nRT
Answer: 190.9K
Explanation:
5.6(14) = 5(.0821)T or (5.6*14)/(5(.0821))
78.4 = 0.4105T
190.9K = T
1. How many molecules are in 4.5 moles?
Answer:
depends on what molecule you are looking for
Explanation:
In one mole of stuff (atoms, molecules, eggses), there are NA individual items of that stuff. So, there are 4.5 × NA BCl3 molecules; i.e. 4.5 × 6.022×1023 ≅ 27×1023 individual molecules of BCl3
How many grams are in 0.500 liters of SBr6?
Please show work if possible or say how to do it
Answer:
250 grams = 0.25 liter
Explanation:
What is the voltage in a circuit is the current is 3 amps and the resistance is 3 ohms
Answer:
9
Explanation:
V=I*R
3*3
Thats the answer
According to the graph, what is the instantaneous speed of the object at 5 seconds? *
Captionless Image
4 m/s
7 m/s
0.25 m/s
3 m/s
Answer:4m/s
Explanation:The reason why that the answer is because I am Smart.
WHEN YOU SEE A BLUE CAR WHAT COLER IS BEING REFLECTED
Answer:
violet
Explanation:
just violet
oh and you spelled "COLER" wrong, its color or colour if you live somewhere else
It is the highest point in a wave.
Answer:
Crest is the highest point of a wave
Convert 10.0 g of iron (II) sulfate to moles.
please explain how to do this! I don't understand
Explanation:
number of moles =mass /relative molecular mass
n=10g/mr(FeSO4)
N=10/(56+32+16×4)
N=10/152
N=0,066 moles
Find the mass of 2.40 moles of CO. gas..
Methanol has the formula of CH3OH and can be produced by the reaction of carbon monoxide with hydrogen gas. CO + 2 H2 === CH3OH + heat Using the above chemical reaction, determine how each of the following actions would affect the equilibrium of the system. a. heating the mixture b. adding an excess of carbon monoxide c. removing the methanol as it is formed d. adding a substance that reacts with carbon monoxide
Answer:
See explanation below
Explanation:
Let's answer this by parts.
a) As the reaction is naturally exothermic (Exerts heat), increasing temperature means that the reaction will move forward the direction where its absorbing heat
, so the equilibrium will be favored to the reactant side.
b) In this case, the addition of CO, which is a reactant will favor the reaction to the product side. This is because putting more quantity in the reactants will cause that the equilibrium constant K, increase it's innitial value, and this favors the product side.
c) In this case, it happens something similar to case b. This will cause that the reaction will have to work to cover the loss of methanol, therefore, equilibrium will move to the product side too.
d) In this case, we are adding another substance that reacts with CO, so it means that the other reactant is being removed, therefore, the reaction will work to cover this loss but also to cover the adding of the new substance, causing that the K decrease it's value, so equilibrium will be favored to the reactants side.
Hope this helps
Which of the following statements about steroid hormones is true?
A. They bind with receptor proteins in the plasma membrane.
B. They bind to carrier proteins in order to be transported in the blood to
their target cells.
C. They are synthesized from epinephrine in the adrenal gland.
D. They are mostly derivatives of the amino acid tyrosine.
Answer:
B. They bind to carrier proteins in order to be transported in the blood to
their target cells.
Explanation:
Steroid hormones are belongs to the class of chemical compound called steroid. Steroid hormones are majorly secreted by three glands - ovaries, testes and adrenal cortex.
Steroid hormones are released in the blood and are allowed to bind to the specific carrier proteins such as corticosteroid-binding globulin and albumin which helps them to carry to the target cells for the functioning.
The steroid hormone binds to receptor proteins in the target cell and not in the plasma membrane
Hence, the correct answer is "B. They bind to carrier proteins in order to be transported in the blood to their target cells."
What is the source of most of the salt in the oceans?
human activities adds salt into the ocean
O rivers and streams carry sediment containing salt to the ocean
O marine fish produce salt adding it into the ocean
wind blows the salt into the ocean
A hydrogen atom is removed from the first carbon atom of a butane molecule and is replaced by a hydroxyl group.
Required:
Draw the new molecule formed.
Answer:
See answer below
Explanation:
In this case, let's draw the butane molecule:
CH₃ - CH₂ - CH₂ - CH₃
According to what the exercise states, we removed an atom of hydrogen from the frist carbon. This could be any of the terminals. I'll grab the first from left to right.
CH₂⁺ - CH₂ - CH₂ - CH₃
When this happens, the atom of carbon is lacking one space and it forms a carbocation.
Followed this step, an hydroxile group replace the atom of hydrogen. The hydroxile is the OH, and when we have an alkane with an OH group in the molecule, we are actually converting this molecule into an alcohol, therefore the molecule formed is:
OH - CH₂ - CH₂ - CH₂ - CH₃Hope this helps
what information is shown in the infographics?
Answer:
An infographic is a collection of imagery, charts, and minimal text that gives an easy-to-understand overview of a topic. As in the example below, infographics use striking, engaging visuals to communicate information quickly and clearly. Infographics are a valuable tool for visual communication.