Question

8 a student measures the mass of a sample of a metallic element, m. then the student heats the sample in air, where it completely reacts to form the compound mo. the student measures the mass of the compound that was formed. which of the following questions can be answered from the results of the experiment? - a. what is the density of m? - b. what is the molar mass of m? - c. what is the melting point of m? - d. what is the melting point of mo? 9. a 42.0 g sample of compound containing only c and h was analyzed. the results showed that the sample contained 36.0 g of c and 6.0 g of h. which of the following questions about the compound can be answered using the results of the analysis? a. what was the volume of the sample? b. what is the molar mass of the compound? c. what is the chemical stability of the compound? d. what is the empirical formula of the compound? mass mass percent of na density color 27.3 g 35.2% 2.05 g cm⁻³ white 10. a jar labeled nacl contains a powder. the table above contains information determined by analyzing a sample of the powder in the laboratory. what information in the table is the most helpful in determining whether the powder is pure nacl? a. mass b. mass percent of na c. density d. color

Explanation:

8.

Step1: Analyze the experiment data

We know mass of M and mass of MO. By subtraction, we can find mass of O in MO.

Step2: Use mole - ratio concept

We know molar mass of O is 16 g/mol. From mass of O, we can find moles of O. Since in MO, mole ratio of M and O is 1:1, we can find moles of M. Then from mass of M and moles of M, we can calculate molar mass of M.

Step1: Calculate moles of C and H

Moles of C = $\frac{36.0\ g}{12\ g/mol}= 3\ mol$, moles of H = $\frac{6.0\ g}{1\ g/mol}=6\ mol$.

Step2: Determine empirical formula

The ratio of moles of C to H is 3:6 = 1:2. So empirical formula is $CH_2$.

Step1: Recall properties of pure substances

For a pure compound like NaCl, the mass - percent of its constituent elements is fixed. Comparing the measured mass - percent of Na in the sample with the theoretical mass - percent of Na in pure NaCl can help determine purity.

Answer:

B. What is the molar mass of M?

9.