Question

How many moles are in 9.50 x 1022 molecules of CO? Be sure to ALL work below and report your answer using the correct number of significant figures.

Answer 1

1.58x10^-1 moles
       To get the number of moles, we simply need to divide by Avogadro's number, which is 6.0221409x10^23. So 9.50x10^22 / 6.0221409x10^23 = ? Since we're dealing with scientific notation, we will deal with the significand and exponents separately. To divide, simply divide the significands as you would normally. 9.50 / 6.0221409 = 1.577512077 And subtract the exponent for the divisor from the exponent from the dividend: 22 - 23 = -1 And we now have 1.577512077 x 10^-1 moles. But that answer has far too many digits given the precision of the data and should only be as precise as the least precise piece of data used. In this problem, we had 8 digits of precision for Avogadro's number and 3 digits of precision for the number of atoms. Of those 2 pieces of data, 3 is the lowest precision and therefore the answer should be rounded to 3 digits, giving 1.58x10^-1 moles.