A student heated a hydrated salt sample with an initial mass of 4.8702 g, After the first heating, the mass had decreased to 3.0662 g (two part question)

Question

1. if the sample was heated to constant weight after reheating, what is the minimum mass that the sample can have after the second weighing? Show how you determined your answer.
2. the student determined that the mass lost by the sample was 1.8053. what was the percent water in the original hydrated sample? show calculation setup.

I think #1 is 1.804 g i got this by subtracting 3.0662 g from 4.8702 g.

I think #2 is 1.8053/4.8702 x 100 = 37.07
Could someone let me know if I am understanding this and doing it correctly?
thanking you in advance

Answer 1

#2 is right.
#1 I'm unsure exactly what is being asked. I think I responded to this question within the last few days but I interpreted the question then as being one of accuracy/precision of weighing. I thought they were after the precision of balances et al. I don't know the answer to #1 (is this all of the question?); at any rate, 1.804 g is not right.
If the original mass was 4.8702 and the final mass after all of the H2O was gone is 1.8053, then the mass at constant weight can't be less than 4.8702-1.8053 = ?
Do have some hints to give for #1. What are you studying(statistics, weighings, balances?). What course is this?

Answer 2

Question number 1 is simply asking what the weight of the second heating needs to be in order for the compound to be "dehydrated." The two weights need to be within .05g in order for the sample to be dehydrated. In this case:
4.8702g(initial mass)- 3.0662(after first heating)= 1.804g
3.0662(mass after first heating)- .05g(maximum variance in mass in order to be dehydrated)= 3.0162g
Keep in mind the .05g variance is used in order to determine "constant weight."

Answer 3

Phil- so is the answer for #1 3.0162? What about the answer for#2, is 37.07% correct?

Answer 4

i think the answer is 1.358