UMM.. I keep coming up with the wrong answer? How do I calculate this?
1. Calculate the number of Li atoms in 9.9 moles of Li.
Express your answer using two significant figures.
2. Calculate the number of CO2 molecules in 3.13×10−2 mole of CO2.
3.Calculate the moles of Cu in 2.4×1021 atoms of Cu.
4.Calculate the moles of C2H6 in 8.60×1023 molecules of C2H6.
There are 6.02E23 atoms in a mole of atoms or 6.02E23 molecules in a mole o molecules; actually, 6.02E23 anythings in a mole of anythings. Just as there are 12 in a DOZEN, 144 in a GROSS, 500 sheets in a REAM of paper,etc, there are 6.02E23 molecules in a mole. It's just another unit like dozen or gross. From your previous work it appears you like to work with unit factors so I'll stick with that.
a. 9.9 mol Li x (6.02E23 atoms/mol) = ? atoms Li.
b. 3.13E-2 mol CO2 x (6.02E23 molecules/mol) = ? molecules CO2
c. 2.4E21 atoms Cu x (1 mol Cu/6.02E23 atoms) = ? mols Cu
d. etc.
You will note that all of these are alike; they consist of taking the number you are given and multiplying by a factor. It's up to you to supply the factor. In this case it's (6.02E23 atoms/1 mol) or (6.02E23 molecules/1 mol) or (1 mol/6.02E23 whatevers)
I'm doing things on Mastering Chemistry dot com my homework.. I thought i was doing it right.. I was doing 9.9 * (6.02E23/1) It didn't like my significant figures.. It was wanting 6.0 * 10^24 as the answer, not 5.95 ugh... Thanks Dr. Bob.. Will probably be posting more for help! this stuff is hard, but you are a great help!!
To calculate each of these values, we need to use Avogadro's number (6.0221 x 10^23) and the given information. Here are the step-by-step calculations for each question:
1. Calculate the number of Li atoms in 9.9 moles of Li:
To find the number of Li atoms, we use the equation:
Number of Li atoms = (9.9 moles Li) x (6.0221 x 10^23 atoms/mole)
= 5.94 x 10^24 Li atoms
Therefore, there are approximately 5.94 x 10^24 Li atoms in 9.9 moles of Li.
2. Calculate the number of CO2 molecules in 3.13×10−2 mole of CO2:
To find the number of CO2 molecules, we use the equation:
Number of CO2 molecules = (3.13×10−2 mole CO2) x (6.0221 x 10^23 molecules/mole)
=1.88 x 10^21 CO2 molecules
Therefore, there are approximately 1.88 x 10^21 CO2 molecules in 3.13×10−2 mole of CO2.
3. Calculate the moles of Cu in 2.4×1021 atoms of Cu:
To find the number of moles of Cu, we use the equation:
Number of moles of Cu = (2.4×1021 atoms of Cu) / (6.0221 x 10^23 atoms/mole)
= 3.98 x 10^-3 moles of Cu
Therefore, there are approximately 3.98 x 10^-3 moles of Cu in 2.4×1021 atoms of Cu.
4. Calculate the moles of C2H6 in 8.60×1023 molecules of C2H6:
To find the number of moles of C2H6, we use the equation:
Number of moles of C2H6 = (8.60×1023 molecules of C2H6) / (6.0221 x 10^23 molecules/mole)
= 1.43 moles of C2H6
Therefore, there are approximately 1.43 moles of C2H6 in 8.60×1023 molecules of C2H6.
To calculate the number of atoms or molecules in a given amount of substance, you need to use Avogadro's number, which is approximately 6.022 × 10^23.
1. To calculate the number of Li atoms in 9.9 moles of Li:
Multiply the given number of moles by Avogadro's number:
9.9 moles Li x (6.022 × 10^23 atoms/mol) = 5.95 × 10^24 atoms of Li
Therefore, there are approximately 5.95 × 10^24 Li atoms in 9.9 moles of Li.
2. To calculate the number of CO2 molecules in 3.13×10^−2 mole of CO2:
Multiply the given number of moles by Avogadro's number:
3.13×10^−2 mole CO2 x (6.022 × 10^23 molecules/mol) = 1.89 × 10^22 molecules of CO2
Therefore, there are approximately 1.89 × 10^22 CO2 molecules in 3.13×10^−2 mole of CO2.
3. To calculate the moles of Cu in 2.4 × 10^21 atoms of Cu:
Divide the number of atoms by Avogadro's number:
2.4 × 10^21 atoms Cu / (6.022 × 10^23 atoms/mol) = 3.98 × 10^−3 moles of Cu
Therefore, there are approximately 3.98 × 10^−3 moles of Cu in 2.4 × 10^21 atoms of Cu.
4. To calculate the moles of C2H6 in 8.60 × 10^23 molecules of C2H6:
Divide the number of molecules by Avogadro's number:
8.60 × 10^23 molecules C2H6 / (6.022 × 10^23 molecules/mol) = 1.43 moles of C2H6
Therefore, there are approximately 1.43 moles of C2H6 in 8.60 × 10^23 molecules of C2H6.