Question

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:

Step1: Recall mole - mass relationship

The number of moles $n=\frac{m}{M}$, where $m$ is the mass and $M$ is the molar mass. To find the mole - ratio of $Ca$ to $Mg$ in the rock, we need the mass of $Ca$ and $Mg$ in the sample and their respective molar masses.

Step2: Identify required columns

Column 3 gives the mass of $Mg$ in the sample ($m_{Mg}$), column 4 gives the mass of $Ca$ in the sample ($m_{Ca}$), column 6 gives the molar mass of $Mg$ ($M_{Mg}$), and column 7 gives the molar mass of $Ca$ ($M_{Ca}$). Using the formula $n=\frac{m}{M}$, we can calculate the number of moles of $Mg$ ($n_{Mg}=\frac{m_{Mg}}{M_{Mg}}$) and the number of moles of $Ca$ ($n_{Ca}=\frac{m_{Ca}}{M_{Ca}}$), and then find the mole - ratio $\frac{n_{Ca}}{n_{Mg}}$.

Answer:

C. 3, 4, 6, 7