A few chemistry questions....please help?

Question

1. Acetylene gas, C2H2, is produced as a result of the following reaction:
CaC2+2H2O=C2H2+Ca(OH)2
a. If 32.o g CaC2 are consumed in this reaction, how many moles of H2O are needed?
b. How many moles of each product would form?

2. When sodium chloride reacts with silver nitrate, silver chloride precipitates. What mass of AgCl is produced from 75.0 g AgNO3?

3. Carbon and oxygen react to form carbon monoxide: 2C+O2=2CO. What masses of carbon and oxygen are needed to make 56.0g CO? Which law does this illustrate?

Please help. I've been working on chemistry ALL evening...I just can't get these few. Thanks.

uh..yeah...i did pay attention...how else would i have gotten all but three done, genius

Answer 1

1) CaC2+2H2O -> C2H2+Ca(OH)2
a) Molar mass of CaC2 = 40 + 2*12 = 64 gram
Therefore 32 gram is 0.5 mol.
This means that 2*0.5 = 1 mol of H2O is needed
b) From the reaction equation we see that 0.5 mol each of C2H2 and Ca(OH)2 are formed.

2) NaCl + AgNO3 -> AgCl + ....
Molar mass of AgNO3 is 107.87 + 14.01 + 3*16.00 = 169.88 gram. Thus 75.0 gram is 75/169.88 = 0.441 mol
Molar mass of AgCl is 107.87 + 35.45 = 143.32 gram. Thus 0.441 mol AgCl is 0.441*143.32 = 63.2 gram

3) 2C+O2 -> 2CO
Molar mass of CO is 12 + 16.00 = 28 gram. Therefore 56.0 gram =2.0 moles.
To create 2 moles of CO, 2mol of C and 1 mol of O2 are needed. This is 2*12=24 gram and 1*16*2=32 gram of O2. As the total mass before and after the reaction are identical this illustrates the law of mass conservation.

Answer 2

I'm not gonna do the math for you cuz I'm lazy like that

1a.
(32.0 g CaC2)/(64 g/mol CaC2)/(1 mole CaC2)*(2 mole H2O) = Answer
That looks like it comes out to 1 doesn't it? But I'm too tired to do math.

1b.
Do you suppose they mean if that same 32g was used? If so...
(32.0g CaC2)/(64 g/mol CaC2)/(1 mole CaC2)*(1 mole C2H2) = moles C2H2
and
(32.0g CaC2)/(64 g/mol CaC2)/(1 mole CaC2)*(1 mole Ca(OH2)) = moles Ca(OH2)

2.
First step is to write out a balanced equation
NaCl + AgNO3 >> AgCl + NaNO3
then there is math
(75.0 g AgNO3)/(170 g/mol AgNO3)/(1 mole AgNO3)*(1 mole AgCl) = Answer

3.
(56.0 g CO)/(28 g/mole CO)/(2 mole CO)*(2 mole C)*(12 g/mole C) = Grams Carbon
and
(56.0 g CO)/(28 g/mole CO)/(2 mole CO)*(1 mole O2)*(32 g/mole O2) = Grams Oxygen
It might illustrate the law of conservation of mass.

This is all stiochiometry stuff. Or however you spell it. The important part is putting in the mole ratio.