Question

A solution contains three components A, B and C, 0.2 mole each, then sum of their mole fractions is:
1. 0.2
2. 0.6
3. 1
4. 3

Answer 1

Correct Answer - Option 3 : 1

Concept:

• The total number of moles of a compound divided by the total number of moles of all constituents gives us mole fraction.
• Mathematically, it can be expressed as:

\({X_1} = \;\frac{{no.\;of\;moles\;of\;sustance\;1}}{{total\;number\;of\;moles\;in\;the\;solution}}\)

• The total mole fraction of a solution always adds up to 1.

\(\sum {X_i = 1} \)

Calculation:

Given:

Moles of component A = B = C = .2

\(mole\;fraction\;of\;A = \frac{{number\;of\;moles\;of\;A}}{{Total\;number\;of\;moles}} = \;\frac{{.2}}{{.6}} = \;.33\)

The mole fraction of B and C will also be .33 each.

\(Total\;molefraction = \;.33 + .33 + .334 = 1\)

Hence, the sum of the mole fraction of the three components A, B, C is 1.