Question

2 mark for review
1\t2\t3\t4\t5\t6\t7
total mass of sample (g)\tmass of c in sample (g)\tmass of mg in sample (g)\tmass of ca in sample (g)\tmolar mass of c (g/mol)\tmolar mass of mg (g/mol)\tmolar mass of ca (g/mol)
98.5\t12.0\t2.4\t36.1\t12.0\t24.3\t40.1
a sample of carbonate rock is a mixture of caco₃ and mgco₃. the rock is analyzed in a laboratory, and the results are recorded in the table above. which columns in the table provide all the information necessary to determine the mole ratio of ca to mg in the rock?
a 1, 2, 5
b 2, 5, 6
c 3, 4, 6, 7
d 2, 3, 4, 5

Explanation:

To find the mole ratio of \( \text{Ca} \) to \( \text{Mg} \), we need the mass of \( \text{Ca} \), mass of \( \text{Mg} \), molar mass of \( \text{Ca} \), and molar mass of \( \text{Mg} \).

• Column 3 gives the mass of \( \text{Mg} \) in the sample.
• Column 4 gives the mass of \( \text{Ca} \) in the sample.
• Column 6 gives the molar mass of \( \text{Mg} \).
• Column 7 gives the molar mass of \( \text{Ca} \).

Using the formula \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \), we can calculate moles of \( \text{Ca} \) and \( \text{Mg} \) from these columns and then find their ratio.

Let's analyze other options:

• Option A (1,2,5): Column 1 (total mass) and Column 2 (mass of C) are not needed for \( \text{Ca} \) and \( \text{Mg} \) moles. Column 5 is molar mass of C, irrelevant.
• Option B (2,5,6): Columns 2 (mass of C) and 5 (molar mass of C) are about carbon, not \( \text{Ca} \) or \( \text{Mg} \).
• Option D (2,3,4,5): Columns 2 (mass of C) and 5 (molar mass of C) are not needed for \( \text{Ca} \) and \( \text{Mg} \) moles.

So only Columns 3, 4, 6, 7 (Option C) provide the necessary info.

Answer:

C. 3, 4, 6, 7