Part 1: Part 2: Part 3: Part 4: Part Questions: Pormuia of a Hydrate uestions: F
ID: 875966 • Letter: P
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Part Questions: Pormuia of a Hydrate uestions: Formu 1. Veronica was in a rush when she did this experiment and only heated the hydrate once. (a) Would this result in her calculating a too high or too low percent of water? Explain. (b) Would her hydrate formula contain more or less water than it should? Explain. 2. This same procedure was followed using a different hydrate. Nick heated a sample of BaCl2 hydrate and found it to be 14.74% water by mass. What was the formula for the hydrate? 3. What is the mass percent of water in cobalt II sulfate heptahydrate? 4. If you had a damp space in a cellar, would you use a deliquescent or an efflorescent substance to dry out the space? Explain. 5. Ben bought a box of washing soda, NayCO3.10H2O, at Stop and Shop. He used a little of it when washing out some old socks. Next month when he was doing his wash again, he noticed the box was a lot lighter than it should have been. Had someone been using Ben's washing soda? What do you think probably happened and why?Explanation / Answer
Ques 1.
a) Due to lack of proper heating by Veronica , the amount of water will be high,so % of water will be high.
b) The hydrate formula will contain more water than it should be. As when calculating the formula we will consider the amount of water in the sample which will be high due to improper heating of the sample.
2. Molecular wt of BaCl2 = 208g/ mole
Let the wt of sample = 100g
which contains = 14.74 % of water = 14.74 of water
so moles of water = 14.74 /18 = 0.82
Now remainin amount = 100-14.74 = 85.26
so moles of BaCl2 = 85.6 / 208 = 0.41 moles
so for each mole fo BaCl2 sample conatins 2 moles of water of hydrate
so formula = BaCl2.2H2O
3. CoSO4.7H2O
Molar mass CoSO4 = 154.9 g/mol
Molar mass CoSO4 . 7H2O = 154.9 + ( 7 x 18 ) = 280.9 g/mol
total mass of water = 7 x 18 = 126
% water = 126 x 100 / 280.9 = 44.9
4. We will use a deliquescent substance as it becomes liquid by absorbing moisture from the air, while efflorscent substance lose water.