Question

A 2.026g sample of a hydrate of sodium carbonate (Na2CO3) is heated to remove water. After heating, the mass of the sample is 0.750 g. Calculate the percentage by mass of water in the sample.

Answer 1

Answer:

62.98 % of the sample of hydrate is water

Explanation:

Step 1: Data given

Mass of the sample of a hydrate of sodium carbonate (Na2CO3) = 2.026 grams

After heating, the mass of the sample is 0.750 g

Molar mass H2O = 18.02 g/mol

Step 2: Calculate mass of water

Mass water = mass of hydrate - mass of sample after heating

Mass water = 2.026 grams - 0.750 grams

Mass water = 1.276 grams

Step 3: Calculate mass % percent of water

Mass % of water = (mass of water / total mass hydrate) * 100 %

Mass % of water = (1.276 grams / 2.026 grams) *100 %

Mass % of water = 62.98 %

62.98 % of the sample of hydrate is water

Answer 2

Answer:

percentage mass of water = 62.98%

Explanation:

The reaction is a decomposition reaction whereby  hydrate of sodium carbonate was heated to remove water . The actual weight of the hydrated compound is 2.026 grams . After heating, the mass of the sample was now 0.750 grams.  The percentage of the water sample can be calculated as follows:

total mass of hydrated sample  = 2.026 grams

mass of sample after heating = 0.750 grams

mass of water removed = 2.026 - 0.750 = 1.276 grams

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

percentage mass of water = 1.276/2.026 × 100

percentage mass of water = 127.6/2.026

percentage mass of water = 62.9812

percentage mass of water = 62.98%