University:
Purdue University
Course:
CHM 11200 | General Chemistry
Academic year:

2021
Views:

127

Pages:

2
Author:

Tripp Floyd

SAMPLE CALCULATIONS for STP and RTP: 1. How many moles of ozone occupy a volume of 3.36 L at STP? 2. What is the mass of 575 L of ammonia gas at RTP? 3. What is the volume occupied by 0.125 g of H2S gas at STP? 4. What mass of carbon dioxide occupies a volume of 1.05 L at RTP? 5. How many oxygen atoms are present in 0.12 L of nitrogen dioxide gas at STP? 6. What is the density of chlorine gas at RTP? 7. What is the density of acetylene gas (C2H2) at 0oC and 760 mmHg? 8. Identify the gaseous element with a density of 1.63 g/L at RTP. 9. Calculate the number of carbon atoms in 35 L of C3H8 (propane) gas at RTP. 10. What if question 9 asked for sodium bicarbonate instead of C3H8? Would the question be done differently if it was an ionic “compound” versus a covalent molecule? 11. What volume will 5.25 X 1022 molecules of methane occupy at STP? 12. Gold has a density of 19.30 g/mL. If your brick of gold occupies a volume of 645 cm3, how many atoms of gold are in your brick? Keep in mind that 1cm =1mL. 13. The density of oxygen gas at STP is 1.43 g/L. If you have 7.8 g of the gas, how many molecules of oxygen gas are in your sample? 14. A sealed container holds 5.0 L of a gas. The gas has a mass of 6.25g. What is the molar mass of this gas at STP? 3 Supplementary Mole Calculations Exercise 1) 2) 3) 4) 5) 6) 7) 8) 9) 10) How many molecules are there in 240 grams of FeF3? How many grams are there in 7.40 x 1023 molecules of AgNO3? How many grams are there in 9.4 x 1025 molecules of hydrogen gas? How many moles of iodine atoms are there in 3.025 x 1024 molecules of N2I6? How many grams of O are there in 1.00 x 1024 molecules of phosphoric acid? How many atoms of Cl are there in 9.3 grams of BeCl2? What mass of SO2(g) would occupy a volume of 225 L at RTP? How many molecules of CO(g) are there in 75.0 L of the gas at STP? What is the density of SiH4(g) at RTP? A gas has a density of 3.56 g/L at STP. What is its molar mass? SAMPLE CALCULATIONS for STP and RTP ANSWER KEY Watch your sig figs! 1) 0.150 mol (mol is the short form for mole or moles)  2) 399 g 3) 0.0821 L 4) 1.89 g 5) 6.45 X 1021 O atoms 6) 2.90 g/L 7) 1.16 g/L 8) 39.9 g / mole which is ARGON gas 9) 2.6 X 1024 C atoms 10) No, the question would not be done differently. You calculate the number of atoms in the same regardless of an ionic compound or covalent molecule. # atoms / ionic cpd OR # atoms / covalent molecule 11) 1.95 L 12) 3.80 X 1025 Au atoms 13) 1.5 X 1023 molecules 14) 28 g/ mole which would be N2 gas! Supplementary Mole Calculations Exercise ANSWER KEY 1) 1.3 X 1024 molecules 2) 209 g 3) 320 g 4) 30.1 moles 5) 79.7 g 6) 1.4 X 1023 Cl atoms 7) 589 g 8) 2.02 X 1024 molecules of CO 9) 1.31 g/L 10) 79.7 g / mol