Question

i did a lab on separation of salt and sand. the initial mass that my teacher gave me was the stock mixture that was: salt= 54.79g; sand= 97.90g. after the experiment my mass were as follow: salt= 1.35g; sand= 3.17g.

question #1 was asking about the % composition of the mixture based on the instructors mass. there was even an equation given.

%composition= mass of component/ x100%
mass of sand+mass of salt

my answer was: sand= 65.11 %; salt= 35.88 %

question #2 was the same but with my mass. i got: sand = 70.13%; salt= 29.86%

question 3 was where i am stuck at. it's talking about

"calculate the expected mass of sand and salt in your sample based on the composition data provided by the instructor".
i asked my teacher to clarify and he said," turn the % in question #1 into a decimal and divide it by the mass of sand or salt i got in my lab which was 3.17g and 1.35g. i did that and the # that i got was : sand = 2.03g ; salt = 0.484 g . from there i went to question #4

question #4. "calculate the % error of you measurements of sand and salt based on expected(2.03g, 0.484g) and observed (3.17g, 1.35g) masses."
(equation).
%error=expected mass - measured mass/ x100
expected masss

i plugged in all the #s but got a negative %. i would like to know if i did something wrong throughout my process. i have asked my classmates as well and they all had gotten a different mass so everyones answer will be different. sorry for the big paragraph, i just wanted to make sure that i am doing it right. sorry again.

Answer 1

See your post above.

Answer 2

i don't get what you mean by "see your post above"? am i doing something wrong or the way im saying it you don't understand it. pls help me.