Question

A penny has a mass of 2.50g and the Moon has a mass of 7.35 X 10²²kg. 

 What is the mass of 1 moIe of pennies? 

 How many moles of pennies have a mass equal to the mass of the Moon? 

Answer 1

According to avogadro's number 1 mole of anything has 6.022 x 10²³ of something

1 moles of pennis will be 6.022 x 10²³ pennies, if 1 penny has a mass of 2.5 grams then 1 mole of pennies will have

6.022 x 10^{23 *} 2.5 = 1.5055 x 10 ²⁴ grams or 1.51 x 10²⁴ (3 significant figures)

part b, the statement says that the moon has a mass of 7.35 x 10²² Kg

we only need to divide the mass of the moon by the mass of 1 mole of pennies but we have to get the same units for both quantities

1 moles pennies =  1.51 x 10 ²⁴ grams , divide it by 1000 to get  1.51 x 10 ²¹ Kg

ratio = 7.35 x 10²² Kg / 1.51 x 10 ²¹ Kg = 48.67 or 48.7 (3 significant figures)

48.7 moles of pennies have the equivalent mass of the moon