Unit 3 Practice Problems

Chem 1115

 

 

1.      Balance the following equations:

 

Na +  H2O à  NaOH +  H2

 

S8 +  O2 à  SO3

 

P4O10    +   H2O   à   H3PO4

 

C3H8   +   O2   à   CO2    +   H2O

 

Al2(SO4)3 +  Ca(OH)2 à  Al(OH)3 +  CaSO4

 

2.      What is the molar mass of Al2(SO4)3 ?

 

3.      How many moles are present in 25.0 g of sulfuric acid?

 

4.      How many grams are present in 0.10 moles of hydrochloric acid?

 

5.      How many molecules are present in 15.0 g of water?

 

6.      How many moles of oxygen atoms are present in 0.25 moles of Al2(SO4)3?

 

7.      How many Na+ ions are present in 15.0 g of Na3PO4?

 

8.      Aluminum hydroxide reacts with sulfuric acid to form aluminum sulfate and water.

 

a.   Write a balanced equation for this reaction.

b.   How many moles of aluminum sulfate with be produced using 0.26 moles of aluminum hydroxide?

c.   How many moles of sulfuric acid are needed to completely react with 0.50 moles of aluminum hydroxide?

d.   How many grams of aluminum sulfate can be produced using 10.0 g of aluminum hydroxide?

e.   How many grams of sulfuric acid are needed to react with 1.25 moles of aluminum hydroxide?

f.    How many kilograms of aluminum hydroxide are needed to react with 5150 g of sulfuric acid?

 

9.      Calcium phosphate reacts with sulfuric acid to form calcium sulfate and phosphoric acid.

 

a.   Write a balanced equation for the reaction.

b.   If 15.0 g of calcium phosphate are reacted with 15.0 g of sulfuric acid in this reaction, which reactant will be the limiting reagent?

c.   Calculate the theoretical yield of calcium sulfate from the reaction described in part b.

 

10.  15.0 grams of a product was obtained from a reaction in which the theoretical yield was 22.0 grams.  Calculate the % yield of the reaction.

 

11.  What is the % composition of barium phosphate?

 

12.  What is the empirical formula of a compound that contains 42.07% Na, 18.89% P, and 39.04% O?

 

13.  What is the molecular formula of a compound that has a molar mass of 90.0 g/mol and an empirical formula of C2H5O?

14.  Write the correct formula for each of the following:

a.   sodium bicarbonate

b.   phosphoric acid

c.   acetic acid

d.   dichlorine heptoxide

e.   dichlorine disulfide

f.    chromium (III) nitrate

g.   tin (IV) oxide

h.   barium phosphate

i.    nitric acid

j.    aluminum acetate

k.   iron (III) sulfide

l.    magnesium hydroxide

m.  zinc carbonate