A chemist has a sample of hydrated Li2SiF6 and it weighs 0.4813 grams. He heats it strongly to drive off the water of hydration, and after heating, he found that the anhydrous compound has a mass of 0.391 grams. What is the percent of water in the hydrate?

percentage of water = 18.76%

Explanation:

A chemist has a sample of hydrated Li2SiF6  and it weighs 0.4813 grams.

The overall weight of the compound is 0.4813 grams.

weight of hydrated sample = 0.4813 grams.

weight of anhydrous compound = 0.391 grams

percentage weight of water = mass of water/mass of the hydrated compound × 100

mass of water = mass of hydrated compound - mass of anhydrous compound

mass of water = 0.4813 - 0.391  = 0.0903 grams.

percentage of water = 0.0903/0.4813 × 100

percentage of water = 9.03/0.4813

percentage of water = 18.761687097

percentage of water = 18.76%

18.8%

Explanation:

Step 1:

The following data were obtained from the question.

Mass of hydrated Li2SiF6 = 0.4813 g

Mass of anhydrous Li2SiF6 = 0.391 g

Step 2:

Determination of the mass of the water in the hydrate.

Mass of water = (Mass of hydrated Li2SiF6) - (Mass of anhydrous Li2SiF6)

Mass of water = 0.4813 - 0.391

Mass of water = 0.0903 g

Step 3:

Determination of the percentage of water in the hydrate.

The percentage of water = Mass of water/ mass of hydrate x 100

The percentage of water = 0.0903/0.4813 x 100

The percentage of water = 18.8%

3, 5–dimethyl–4–heptanethiol.

Explanation:

To name the compound given in question above, we must:

1. Determine the longest continuous carbon chain. This gives the parent name of the compound.

2. Determine the functional group of the compound and give it the lowest possible count.

3. Identify the substituent group attached.

4. Give the substituent the lowest possible count.

5. Combine the above to obtain the name of the compound.

Now, let us name the compound given in question with the above ideas in mind. This can be achieved as shown below:

1. The longest continuous carbon chain is 7 i.e heptane.

2. The functional group is –SH i.e thiol. We shall add thiol to end end of heptane making the parent to be heptanethiol. The functional group is at carbon 4.

3. The substituent attached is CH3 i.e methly.

4. There are two CH3 attached to compound and they are at carbon 3 and 5 respectively.

5. The name of the compound is:

3, 5–dimethyl–4–heptanethiol.