Question

Molecular chlorine and molecular fluorine combine to form a gaseous product. Under the same conditions of temperature and pressure it is found that one volume of Cl_2 reacts with three volumes of F_2 to yield two volumes of the product. What is the formula of the product?

Answer 1

Explanation:

According to the law of conservation of mass, a chemical reaction can only be balanced when the number reactants equal the number of products.  

The reaction between molecular chlorine and fluorine is given as follows.

              $Cl_{2}(g) + 3F_{2}(g) \rightarrow 2Cl_{x}F_{y}(g)$

where,     x = subscript of chlorine

               y = subscript of fluorine

Number of atoms on reactant side are as follows.

• Cl = 2
• F = 6

Number of atoms on product side are as follows.

• Cl = 2
• F = 2

Therefore, to balance the given chemical equation, place the value of x as 1 and value of y as 3 on the product side.

Hence, the balanced chemical equation is as follows.

               $Cl_{2}(g) + 3F_{2}(g) \rightarrow 2ClF_{3}(g)$

Answer 2

In this equation

1 Cl2 + 3 F2---> 2 ClxFy

those coefficients are in MOLE (or molecule) ratios. BUT for gases at the same temp and pressure, they are also VOLUME ratios.. why? PV = nRT, V = nRT/P. if RT/P = constant.. V1/n1 = V2/n2 --> n1/n2 = V1/V2..make sense? mole ratios
= volume ratios

so.. what are x and y?
1 Cl2 + 3 F2---> 2 ClxFy

2 Cl's on the left.. x must = 1
6 F2's on the left. y must be 3

1 Cl2 + 3 F2---> 2 ClF3