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.
See your post above.
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.
No problem, let's go step by step to make sure we have the correct answers.
For question #1, you correctly used the formula to calculate the percent composition based on the instructor's mass. The formula is:
% composition = (mass of component / (mass of sand + mass of salt)) * 100
Using the given values, we have:
% composition of salt = (54.79 g / (97.90 g + 54.79 g)) * 100 = 35.88%
% composition of sand = (97.90 g / (97.90 g + 54.79 g)) * 100 = 64.12%
So, the sand is 64.12% and the salt is 35.88% based on the instructor's mass.
For question #2, you calculated the percent composition based on your measured mass. The formula remains the same, but you use your measured values this time.
% composition of salt = (1.35 g / (3.17 g + 1.35 g)) * 100 ≈ 29.86%
% composition of sand = (3.17 g / (3.17 g + 1.35 g)) * 100 ≈ 70.14%
So, the sand is approximately 70.14% and the salt is approximately 29.86% based on your measured mass.
Now, for question #3, you need to calculate the expected mass of sand and salt in your sample based on the percent composition provided by the instructor. To do this, you will convert the percent composition to decimal form and multiply it by the total mass of your sample.
Expected mass of salt = (35.88% / 100) * (1.35 g + 3.17 g) ≈ 1.64 g
Expected mass of sand = (64.12% / 100) * (1.35 g + 3.17 g) ≈ 2.88 g
So, the expected mass of salt in your sample is approximately 1.64 g and the expected mass of sand is approximately 2.88 g.
Finally, for question #4, you need to calculate the percent error of your measurements compared to the expected masses.
% error of salt = ((1.64 g - 1.35 g) / 1.64 g) * 100 ≈ 16.46%
% error of sand = ((2.88 g - 3.17 g) / 2.88 g) * 100 ≈ -9.95%
It seems that you made a mistake in the calculation of the percent error for sand. The formula for the percent error is:
% error = ((expected mass - measured mass) / expected mass) * 100
So, the correct percent error of sand is approximately -9.95%. The negative sign indicates that your measured mass of sand is slightly higher than the expected mass.
I hope this clears up any confusion. Let me know if you have any further questions!