and we had to round this was the question was to again
calculate the number of moles in each of the following masses
a)64.1 g of aluminum
b)28.1 g of silicon
c)0.255 g of sulfur
d)850.5 g of zinc
a) 64/27 = 2.4 mols b) 28.1g/28=1.0 mol c) 0.255/32=.0080 d)850.5/65 =13.076. I think i made some mistakes can u see if im on the right track or correct me if im wrong.. thanks in advance
also the answer has to be rounded and written in scientific notation form which ive failed and need help
#1. You are in the ball park but you are allowed 3 significant figures with the 64.1 so you should have at least one more place in your answer. I used 26.98 for Al.
#2 is ok but the answer should be 1.00.
#3 should be to 3 places. I find 0.00795 (and I used 32.066 for S, not 32).
#4. I used 65.39 for Zn and obtained 13.00658 which I would round to 13.01.
okay but my teacher said we were supposed to round the atomic mass.. so would that change the answer?
You're on the right track, but there are a few mistakes in your calculations and rounding. Let's go through each calculation step-by-step:
a) Aluminum (Al) has a molar mass of approximately 27 g/mol.
To calculate the number of moles in 64.1 g of aluminum, divide the given mass by the molar mass:
64.1 g / 27 g/mol = 2.374074074074074 moles
Round this to the correct number of significant figures or decimal places (in this case, one decimal place):
2.4 moles (rounded to one decimal place)
b) Silicon (Si) has a molar mass of approximately 28 g/mol.
To calculate the number of moles in 28.1 g of silicon, divide the given mass by the molar mass:
28.1 g / 28 g/mol = 1.0035714285714286 moles
Round this to the correct number of significant figures or decimal places (in this case, one decimal place):
1.0 moles (rounded to one decimal place)
c) Sulfur (S) has a molar mass of approximately 32 g/mol.
To calculate the number of moles in 0.255 g of sulfur, divide the given mass by the molar mass:
0.255 g / 32 g/mol = 0.00796875 moles
Round this to the correct number of significant figures or decimal places (in this case, two decimal places):
0.0080 moles (rounded to two decimal places)
d) Zinc (Zn) has a molar mass of approximately 65 g/mol.
To calculate the number of moles in 850.5 g of zinc, divide the given mass by the molar mass:
850.5 g / 65 g/mol = 13.077692307692307 moles
Round this to the correct number of significant figures or decimal places (in this case, one decimal place):
13.1 moles (rounded to one decimal place)
Remember to always consider the correct number of significant figures or decimal places when rounding your answers. In scientific notation, you may write the numbers as follows:
a) 2.4 moles can be written as 2.4 × 10^0 mol
b) 1.0 moles can be written as 1.0 × 10^0 mol
c) 0.0080 moles can be written as 8.0 × 10^-3 mol
d) 13.1 moles can be written as 1.31 × 10^1 mol
Make sure to write the numbers with the correct powers of 10 to represent the value in scientific notation.