mass of crucible- 18.50g
mass of crucible+hydrate- 19.50g
mass of crucible+anhydrous salt 1st heating- 19.10g
mass of crucible+anhydrous salt 2nd heating- 19.10g
Questions: 1. calculate mass of water lost from your sample
2. calculate % of water in sample CuSO4*5H2O
3. calculate % error using actual value calculated in the prelab
4. why is it important to make sure all masses of salt agree after each heating?
I shall be happy to help you through this but I don't intend to work it for you. If you will tell me what you don't understand I can show you where to start.
To answer these questions, we can follow the steps below:
1. To calculate the mass of water lost from the sample, we need to find the difference in mass of the crucible with the hydrate (19.50g) and the crucible with the anhydrous salt after the second heating (19.10g).
Mass of water lost = mass of crucible with hydrate - mass of crucible with anhydrous salt (after second heating)
= 19.50g - 19.10g
= 0.40g
Thus, the mass of water lost from the sample is 0.40g.
2. To calculate the percentage of water in the sample CuSO4⋅5H2O, we need to find the mass of water lost (0.40g) and the initial mass of the hydrate (18.50g).
% Water in CuSO4⋅5H2O = (mass of water lost / initial mass of hydrate) x 100
= (0.40g / 18.50g) x 100
≈ 2.16%
Therefore, the percentage of water in the CuSO4⋅5H2O sample is approximately 2.16%.
3. To calculate the percentage error using the actual value calculated in the prelab, we need to compare the calculated percentage of water in the sample (from step 2) with the prelab's actual value. Let's assume the actual value is 2.50%.
% Error = |(calculated value - actual value) / actual value| x 100
= |(2.16% - 2.50%) / 2.50%| x 100
= 14.40%
So, the percentage error is 14.40%.
4. It is important to make sure all masses of salt agree after each heating to ensure that all the water has been fully removed from the sample. If the masses of the anhydrous salt do not agree between the first and second heating, it indicates that the sample has not been heated for a sufficient amount of time, or at a high enough temperature, to remove all the water. This could result in inaccurate measurements and calculations for mass loss and percentage of water in the sample. Therefore, consistent masses after each heating confirm that the sample has been properly dehydrated.