Consider the reaction between two solutions, X and Y, to produce substance Z: aX + bY → cZ When 500. mL of a 1.8 M solution of X is combined with 500. mL of a 1.8 M solution of Y, the resulting solution has a concentration of 0.60 M Y and 0.60 M Z. No more of substance X remains in the flask. 1. How many moles each of X and Y are present before the reaction occurs? 2. How many moles each of Y and Z are present after the reaction occurs? 3. How many moles each of X and Y have reacted? 4. What is the balanced equation for this reaction?

1. 0.90 are the initial moles of X and Y

2. 0.60 moles are the moles of Y and Z after the reaction

3. 0.90 moles of X and 0.30 moles of Y

4. 3X + 1Y → 2Z

Explanation:

1. For the reaction, initial moles of X and Y are:

500mL = 0.500L × (1.8 moles / L) = 0.90 are the initial moles of X and Y

2. After the reaction. The total volume is 500mL + 500mL = 1L

Moles Y and Z = 1L × (0.60 moles / 1L) = 0.60 moles are the moles of Y and Z after the reaction

3. As there is no moles of X after the reaction, all X reacts, that is 0.90 moles of X. And moles of Y that reacts are 0.90 mol - 0.60mol = 0.30 moles of Y

4. That means 3 moles of X reacts per mole of Y 0.90/0.30 = 3. Also, 2 moles of Z are produced per mole of Y 0.60/0.30 = 2.

That means balanced equation is:

aX + bY → cZ