Answer:
1. 5g
2. 2.3g
3. 2.7g
4. 0.02mol
5. 0.13mol
6. 7moles
Explanation:
From the question, the following were obtained:
Mass of empty tube = 13.5g
Mass of empty tube + hydrated salt = 18.5g
Mass of tube + anhydrous salt = 16.2g
1. Mass of empty tube = 13.5g
Mass of empty tube + hydrated salt = 18.5g
Mass of hydrated salt = 18.5 — Mass of empty tube
Mass of hydrated salt = 18.5 — 13.5 = 5g
2. Let us calculate the mass of the anhydrous salt.
Mass of tube + anhydrous salt = 16.2g
Mass of empty tube = 13.5g
Mass of anhydrous salt = 16.2 — Mass of empty tube = 16.2 — 13.5
Mass of anhydrous salt = 2.7g
Now we can calculate the mass of the water evolved as follows:
Mass of water = Mass of hydrated salt — Mass of anhydrous
Mass of water = 5 — 2.7 = 2.3g
3. Mass of empty tube = 13.5g
Mass of anhydrous salt = 16.2 — Mass of empty tube = 16.2 — 13.5
Mass of anhydrous salt = 2.7g
4. MM of CaCl2 = 40 +(2x35.5) = 40 + 71 = 111g
Mass of CaCl2 = 2.7g
Number of mole = Mass /Molar Mass
Number of mole of CaCl2 = 2.7/111 = 0.02mol
5. MM of H2O = (2x1) +16 = 2 + 16 = 18g/mol
Mass of H2O = 2.3g
Number of mole = Mass /Molar Mass
Number of mole of H20 = 2.3/18 = 0.13mol
6. To get the mole of water in the molecular formula, we will find the ratio of the number of mole of anhydrous salt to water as shown below:
Mole anhydrous : mole of water ie
0.02 : 0.13 = 1 : 7
Therefore, the mole of water in the formula is 7 ie
CaCl2.7H20
