Homework due Tuesday, July 16

1. The law of conservation of matter states that matter is neither created nor destroyed in a chemical reaction.

2. A scientific law summarizes what has been learned according to careful observation of nature.

3. Expressions such as "using up" and "throwing away" can be very misleading since one might think that matter is lost since you are getting rid of it; however, matter is neither created nor destroyed and atoms are forever there.

4.

a.

Reactants: Sn-1 H-1 F-1

Products: Sn-1 H-2 F-2

·      not balanced because the number of atoms per element on the reactant and products side is not the same, or balanced.

b.

 Reactants: Si-1 O-2 C-1

Products: Si-1 O-1 C-2

·      not balanced because the number of atoms per element on the reactant and products side is not the same, or balanced.

c.

Reactants: Al-1 O-3 H-6 Cl-3

Products: Al-1 O-3 H-6 Cl-3

·      balanced because the number of atoms per element on the reactant and products side is the same.

5.

a. The coefficient for H (g) is 3

b. The coefficient for NH3 gas is 2

c. The coefficient for N (g) is 1

6.

a. 1 WO3 + 3 H2 --> 1 W + 3 H2O

b. 2 PbS + 3 O2 --> 2 PbO + 2 SO2

c. 4 Fe + 3 O2 --> 2 Fe2O3

7. 

a. 1 Ca3(PO4)2 + 3 H2SO4 --> 2 H3PO4 + 3 CaSO4

b. 2 C8H18 + 25 O2 --> 16 CO2 + 18 H2O

8. 

a. Yes

Reactants: Na-2  S-1 O-4  K-2  Cl-1

Products: Na-2  S-1 O-4 K-2 Cl-1

b. No, because the subscripts remain the same, but the coefficients are altered to balance the equation. 

c. 1 Na2SO4 + 2 KCl --> 2 NaCl + 1 K2SO4

9. It would take 400,000 seconds to spend one mole of dollars.  (10 * 10^9)

10.

a. O2: 32 g

b. O3: 48 g

c. CaCO3: 100 g

d. Mg(OH)2: 58 g

e. C9H8O4: 180 g