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
No problem, I'm here to help! Let's go through your calculations step-by-step to see if there are any mistakes.
Question 1: Calculating the % composition of the mixture based on the instructor's mass.
The equation given is:
% composition = (mass of component / mass of total mixture) * 100
For the salt:
% composition of salt = (54.79g / (97.90g + 54.79g)) * 100
% composition of salt = (54.79g / 152.69g) * 100
% composition of salt = 35.9%
For the sand:
% composition of sand = (97.90g / (97.90g + 54.79g)) * 100
% composition of sand = (97.90g / 152.69g) * 100
% composition of sand = 64.1%
Based on these calculations, it seems like you have a small error in your answer for question 1. The correct % composition is salt: 35.9% and sand: 64.1%.
Question 2: Calculating the % composition of the mixture based on your measurements.
Using the same formula, the calculations would be as follows:
For the salt:
% composition of salt = (1.35g / (3.17g + 1.35g)) * 100
% composition of salt = (1.35g / 4.52g) * 100
% composition of salt = 29.8%
For the sand:
% composition of sand = (3.17g / (3.17g + 1.35g)) * 100
% composition of sand = (3.17g / 4.52g) * 100
% composition of sand = 70.2%
Based on these calculations, your answer for question 2 is correct. The % composition is salt: 29.8% and sand: 70.2%.
Question 3: Calculating the expected mass of sand and salt in your sample.
To calculate the expected mass, you need to convert the % composition into decimals and then multiply it by the total mass of sand or salt in your sample.
For the sand:
Expected mass of sand = 70.2% (0.702) * 3.17g
Expected mass of sand = 2.22g
For the salt:
Expected mass of salt = 29.8% (0.298) * 1.35g
Expected mass of salt = 0.403g
Based on these calculations, your answer for question 3 is incorrect. The expected mass should be Sand: 2.22g and Salt: 0.403g.
Question 4: Calculating the % error of your measurements.
To calculate the % error, you can use the formula given:
% error = abs(expected mass - measured mass) / expected mass * 100
For the sand:
% error of sand = |2.22g - 3.17g| / 2.22g * 100
% error of sand = 0.95g / 2.22g * 100
% error of sand = 42.8%
For the salt:
% error of salt = |0.403g - 1.35g| / 0.403g * 100
% error of salt = 0.947g / 0.403g * 100
% error of salt = 235.1%
It seems like your calculation for question 4 is also incorrect. The correct % error is Sand: 42.8% and Salt: 235.1%.
I hope this helps clarify your calculations! If you have any further questions, feel free to ask.
No problem, let's go through your process step by step to see if there were any errors.
Question #1:
To find the percentage composition of the mixture based on the instructor's mass, you used the formula:
%composition = (mass of component / mass of sand + mass of salt) * 100
Your calculations were:
Sand = (97.90g / 152.69g) * 100 = 64.11%
Salt = (54.79g / 152.69g) * 100 = 35.88%
It seems like there was a typo in your answer for the percentage composition of sand. It should be 64.11% instead of 65.11%.
Question #2:
To find the percentage composition of the mixture based on your mass, you used the same formula:
%composition = (mass of component / mass of sand + mass of salt) * 100
Your calculations were:
Sand = (3.17g / 4.52g) * 100 = 70.13%
Salt = (1.35g / 4.52g) * 100 = 29.86%
These calculations are correct.
Question #3:
To calculate the expected mass of sand and salt in your sample based on the composition data provided by the instructor, you were told to turn the percentage into a decimal and divide it by the mass of sand or salt you obtained.
For the expected mass of sand:
Expected sand mass = (64.11% * 4.52g) = 2.90g
For the expected mass of salt:
Expected salt mass = (35.88% * 4.52g) = 1.62g
It seems that you made an error in your calculations. The expected mass of sand should be 2.90g, not 2.03g. The expected mass of salt should be 1.62g, not 0.484g.
Question #4:
To calculate the percent error of your measurements, you used the formula:
%error = (expected mass - measured mass) / expected mass * 100
For sand:
%error = (2.90g - 3.17g) / 2.90g * 100 = -9.31%
For salt:
%error = (1.62g - 1.35g) / 1.62g * 100 = 16.67%
Your calculations are correct. The negative sign in the percent error for sand indicates that your measured value is slightly higher than the expected value.
To summarize, the errors in your calculations were in the percentage composition of sand in question #1 and the expected mass of sand and salt in question #3. Correcting those errors, the expected mass of sand should be 2.90g and the expected mass of salt should be 1.62g.