University:
Glendale Community College
Course:
CHM151 | General Chemistry
Academic year:

2020
Views:

483

Pages:

2
Author:

chin5tgu

Worksheet on Moles Three conversions to remember about chemicals – usually used when we are asking about just one chemical: 1. How many atoms are in 40.08 grams of calcium? 2. One mole of magnesium would contain how many atoms? 3. How many atoms are in 5.55 moles of silver? 4. How many moles are in 5.55 x 1033 molecules of H2SO4? 5. What is the molar mass of sodium carbonate? 6. What is the molar mass of nickel(III) sulfate? 7. How many moles are in 88.88 grams of calcium? 8. How many grams is 1.25 moles of potassium bromide? 9. 3.50 grams of gold would contain how many atoms? 10. How many liters is 0.975 moles of laughing gas at STP? 11. How many liters is 3.59 x 1019 atoms of argon gas at STP? 12. What is the percent oxygen in sulfuric acid, H2SO4? 13. What is the percent hydrogen in water? Answers 1. 40.08 grams of calcium is one mole (see Periodic Table), and one mole is 6.02 x 1023 atoms. 2. One mole of anything is 6.02 x 1023, so it is 6.02 x 1023 Mg atoms. 3. 5.55 mol Ag ( 6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠 1 𝑚𝑜𝑙 ) = 3.34 x 1024 atoms Ag 1 𝑚𝑜𝑙 4. 5.55 x 1033 molecules (6.02 𝑥 1023 𝑚𝑜𝑙𝑒𝑐𝑢𝑙𝑒𝑠 ) = 9.22 x 109 moles H2SO4 5. Na2CO3 adding up the masses of all the atoms = 105.99 g/mol 6. Ni2(SO4)3 is 405.59 g/mol 1 𝑚𝑜𝑙 7. 88.88 g Ca (40.08 𝑔 ) = 2.218 mol Ca 8. 1.25 mol KBr ( 119.00 𝑔 1 𝑚𝑜𝑙 1 𝑚𝑜𝑙 9. 3.50 g Au (196.97 𝑔 ) ( ) = 149 grams 6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠 1 𝑚𝑜𝑙 ) = 1.07 x 1022 atoms Au 22.4 𝐿 10. 0.975 mol (1 𝑚𝑜𝑙 ) = 21.8 L gas 1 𝑚𝑜𝑙 22.4 𝐿 11. 3.59 x 1019 atoms Ar (6.02 𝑥 1023 𝑎𝑡𝑜𝑚𝑠 ) (1 𝑚𝑜𝑙 ) = 0.00134 L Ar gas 12. Four oxygens = 64.00 grams, H2SO4 total = 98.09 grams. 64.00 𝑔 So percent oxygen is ( 98.09 𝑔 ) x 100% = 65.25% 13. Two hydrogens in water = 2.02 grams, H2O = 18.02 grams 2.02 𝑔 So percent H is (18.02 𝑔) x 100% = 11.2%