Consider the balanced chemical equation \(2 \mathrm{~A}+\mathrm{B} \rightarrow 2 \mathrm{C}+\mathrm{D}\) When \(8.0 \mathrm{~g}\) of A reacts completely with \(6.0 \mathrm{~g}\) of \(\mathrm{B}\), \(10.0 \mathrm{~g}\) of \(\mathrm{C}\) and \(4.0 \mathrm{~g}\) of \(\mathrm{D}\) are produced. Assuming the yield is \(100 \%\), (a) Which has a greater molar mass, A or C? (b) Which has a greater molar mass, A or B? (c) Which has a greater molar mass, A or D? (d) If the molar mass of \(\mathrm{A}\) is \(24.0 \mathrm{~g} / \mathrm{mol}\), determine the molar mass of \(\mathrm{B}, \mathrm{C}\), and \(\mathrm{D}\).

Short Answer

Expert verified
(a) C has a greater molar mass than A. (b) B has a greater molar mass than A. (c) A and D have equal molar masses. (d) The molar masses of B, C, and D are 36.0 g/mol, 30.0 g/mol, and 24.0 g/mol, respectively.

Step by step solution

01

Calculate mole ratios A and B

To calculate the mole ratio between reactants A and B, we need to divide the mass of each reactant by its respective molar mass (we will denote these molar mass as M_A, M_B, M_C, and M_D for the four substances, respectively). Since we know the molar mass of A, we can calculate the number of moles of A. Then, we can determine the ratio of moles of A to moles of B using the balanced chemical equation. n_A = \(\frac{mass_A}{M_A}\) = \(\frac{8.0~g}{24.0~g/mol}\) = \(0.333~mol\) Since the balanced chemical equation states there is a 2-to-1 ratio for A to B, we can determine the number of moles of B: n_B = \(\frac{1}{2}\)n_A = \(\frac{1}{2}\)(0.333 mol) = \(0.167~mol\)
02

Calculate the molar mass of B

Now that we know the number of moles of B, we can calculate the molar mass using the mass of B. M_B = \(\frac{mass_B}{n_B}\) = \(\frac{6.0~g}{0.167~mol}\) = \(36.0~g/mol\)
03

Determine which has a greater molar mass: A or B

Since the molar mass of A is 24.0 g/mol and the molar mass of B is 36.0 g/mol, B has a greater molar mass than A.
04

Calculate the number of moles of C and D

Using the balanced chemical equation, we see that the mole ratio of A:C is 2:2 = 1:1 and A:D is 2:1. Therefore, the number of moles of C must be equal to the number of moles of A, and the number of moles of D must be equal to half the number of moles of A: n_C = n_A = \(0.333~mol\) n_D = \(\frac{1}{2}\)n_A = \(0.167~mol\)
05

Calculate the molar mass of C and D

We can calculate the molar masses of C and D using their masses and the calculated number of moles. M_C = \(\frac{mass_C}{n_C}\) = \(\frac{10.0~g}{0.333~mol}\) = \(30.0~g/mol\) M_D = \(\frac{mass_D}{n_D}\) = \(\frac{4.0~g}{0.167~mol}\) = \(24.0~g/mol\)
06

Determine which has a greater molar mass: A, C, and D

Comparing the molar masses of A, C and D: - Molar mass of A: 24.0 g/mol - Molar mass of C: 30.0 g/mol - Molar mass of D: 24.0 g/mol So, C has a greater molar mass than A, and A and D have equal molar masses. The answers to the given questions are: (a) C has a greater molar mass than A. (b) B has a greater molar mass than A. (c) A and D have equal molar masses. (d) The molar masses of B, C, and D are 36.0 g/mol, 30.0 g/mol, and 24.0 g/mol, respectively.

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