$word_{count}$: 200

Step-by-step approach for Raoult's law problems: (1) Identify if solution is ideal or shows deviations. (2) Convert given masses to moles using molar masses. (3) Calculate mole fractions: $x_A$ = $\frac{n_A}{n_A + n_B}$. (4) Apply $P_A$ = $x_A$*P_A_{std} for each component. (5) Find $P_{total}$ = $P_A$ + $P_B$. (6) For vapour composition: $y_A$ = $\frac{P_A}{P_total}$. Common problem types: Given $x_A$ and $P_{std}$ values, find $P_{total}$ and $y_A$. Given $y_A$ and $P_{std}$ values, find $x_A$ (requires algebra). Given $P_{total}$ and one $P_{std}$, find the other or find composition. For non-volatile solute: $P_{solution}$ = $x_{solvent}$ * P_{solvent}_{std}. RLVP = $\frac{delta_P}{P_std}$ = $x_{solute}$. Traps: (a) confusing mass fraction with mole fraction, (b) not converting grams to moles before calculating x, (c) using RLVP formula when both components are volatile, (d) forgetting that $y_A$ + $y_B$ = 1. For immiscible liquids: $P_{total}$ = P_A_{std} + P_B_{std} (each exerts full vapour pressure). This is tested as steam distillation problems.