Week 1 Hw #7

[Sharon Chu 3I]

"A solution of CaCl2 in water forms a mixture that is 41.0% calcium chloride by mass. If the total mass of the mixture is 928.7 g, what masses of CaCl2 and water were used?"

I inputted the answers as
CaCl2: 380.8g
H2O: 547.9g
However I thought these answers would be 381g and 548g respectively just because in the original problem we are given a 3 significant digit value of 41.0%, therefore shouldn't the answers be in 3 significant digits?

[Alexander Moroz 1B]

Did you get it right with 4 significant figures? I inputted my answers with 3 significant figures for the same reason and I got it correct too.

[Sharon Chu 3I]

Did you get it right with 4 significant figures? I inputted my answers with 3 significant figures for the same reason and I got it correct too.

I did get it correct, but on an exam I think the answer would probably be 3 sig digs

[Hannah_Pon_1F]

Hi,
I believe for the Achieve HW sometimes it will accept a range for the correct answer so that might be why it accepted it as correct. But on exams, I would definitely use the correct sig figs for your answers, which in this case would be 3 sig figs for this question.
Hope this helps!

[Chem_Mod]

Hello all,

I believe Hannah is correct in saying that achieve will accept a range for the correct answer, and she is absolutely correct that for the purpose of exams the correct number of sig figs should be used! The correct number of sig figs, in this case, is 3 (as many of you said) because our lowest number of sig figs from our provided data was 41.0%, which has 3 sig figs.

-Gabby (TA for 1E, 1K, and 1L)

[Sharon Chu 3I]

Hi,
I believe for the Achieve HW sometimes it will accept a range for the correct answer so that might be why it accepted it as correct. But on exams, I would definitely use the correct sig figs for your answers, which in this case would be 3 sig figs for this question.
Hope this helps!

Ahhh okay, yes thank you !!

[Edmond Chu 1C]

Achieve allows you to be off on your answer by a certain amount. So, if you are very close to the answer, they will say it is correct. But on the test, definitely write your answer in terms of correct sig figs.