Expert: Richard J. Raridon - 1/1/2008

Question
Hi, I'm having some trouble with these chem. problems.

1. How many grams of I2 are produced when 32 g of Br2 react with excess KI?

2. What volume of O2 at 298K and 2 atm is required to react completely with 2L of Methane at the same temperature and pressure?

3. How many atoms of hydrogen are present in 10g of methane?

4. How much 0.5 M KCl solution is required to react completely with 100 mL of 2M AgNO3 solution?
This is the balanced equation: KCl + AgNO3---->AgCl + KNO3

Answer
1. Br2 + 2KI -> I2 +2KBr
mol. wt of Br2 = 141.82, mol. wt. of I2 = 253.8
so 253.8/141.82 = x/32 and x = 57.3g
2. CH4 + 2O2 -> CO2 +2H2O
It takes twice the volume of O2 as CH4 so that's 4L
3. (10/16)(4)(6x10^23) = 1.5x10^24 atoms
4. 100(2) = x(0.5) so x = 400 ml