Moles Worksheet 12/5/2006

Ch100: Fundamentals for Chemistry 1 Moles Worksheet 4/29/2018

1. You have a 26.98 g piece of aluminum. a) How many moles are in 26.98 g of Al?

b) How many atoms are in 26.98 g of Al?

c) How many moles are in 5.00 g of Al?

d) How many atoms are in 5.00 g of Al?

2. You have a 20.00 g sample of chlorine gas.

a) How many moles of Cl2 are in the 20.00 g sample?

b) How many molecules are in 20.00 g of Cl2?

c) How many Cl atoms are in 20.00 g of Cl2?

d) How many moles of Cl2 are in a 5.00 g sample?

e) How many molecules of Cl2 are in 5.00 g? Ch100: Fundamentals for Chemistry 2 Moles Worksheet 4/29/2018

3. You have a sample containing 10.00 g of AlCl3?

a) What is the molecular mass of AlCl3?

b) How many moles of AlCl3 are in the sample?

c) How many moles of Al3+ are in the sample?

d) How many moles of Cl- are in the sample?

e) How many grams of Al3+ are in the sample?

f) How many grams of Cl- are in the sample?

4. You dissolve 25.00 g of AlCl3 in 1.0 L of de-ionized H2O.

a) How many moles of AlCl3 are dissolved?

b) How many molecules of AlCl3 are dissolved?

c) Using the information above, calculate how much volume of this solution you would

need to get 5.00 g of AlCl3. Ch100: Fundamentals for Chemistry 3 Moles Worksheet 4/29/2018

5. You have a flask containing 150. g of H2O (volume is 150. mL).

a) How many moles of H2O are in 150. g?

b) How many molecules of H2O are 150. g?

c) What is the mass percent of H and O, respectively, in H2O?

d) How much water (in grams) is needed to have obtain 10.0 grams of oxygen?

6. In the chemistry lab, you produce 10.0 grams of hydrogen gas from the following chemical reaction:

2HCl (aq) + Zn (s)  H2 (g) + ZnCl2 (aq)

a) What is the molar mass of H2?

b) How many moles of H2 are in 10.0 g?

c) How many moles of Zn are needed to produce 10.0 g of H2?

d) How many grams of Zn are needed to produce the 10.0 g of H2? Ch100: Fundamentals for Chemistry 4 Moles Worksheet 4/29/2018

7. Nuclear Chemistry: Nuclear Fusion During a nuclear fusion reaction, 2 nuclei combine to form the larger nucleus of a larger atom; in the process a large amount of heat energy is released. Consider the fusion of hydrogen-1, 1H to form helium-4 (4He), beta particles (+) and gamma photons (): 4 1H  4He + 2 + + 2  a) Calculate the mass of the four hydrogen 1 atoms.

b) Calculate the total mass of the helium-4 atom and the beta particles. Notes: 1) gamma photons are electromagnetic energy and do not have mass; and 2) beta particles have the same mass as electrons.

c) Calculate the mass deficit (m) between the reactants (a) and the products (b). This is the lost mass that is released as energy!

d) According to Einstein’s famous equation, E = (m)c2, where c = 2.998 x 108 m/s (the speed of light in vacuum) and m is the mass deficit (lost mass) during the reaction. Calculate the energy equivalent (in Joules) for the mass deficit in this nuclear fusion reaction; this is the amount of energy released by this nuclear process.

e) Convert the energy from Joules to calories.

f) Calculate the energy released per mole of helium-4 produced during this process.

g) If 1.00 mole of helium-4 is produced by this process, how many grams is it?