1. Entry Task: March 5 th -6 th Block #1 Entry Task Question: 2Mg + O 2  2MgO How many grams of Mg are needed to produce 35 moles of MgO? You have ~10 minutes

2. Agenda: Discuss Label Reasoning ws 1 Stoich Notes #2 Grams  Grams HW: Mole Ratio Lab

3. Avervision answers

4. I can… Identify the quantitative relationship in a balanced chemical equation Determine the mole ratios from a balanced chemical reaction Use the sequence of steps used in solving stoichiometric problems

6. Grams to Gram ratio Chromium metal reacts with oxygen gas to create chromium III oxide. ___Cr + ___O 2  ___Cr 2 O 3 243

7. 243 a. How many grams of Chromium III oxide were produced if 35.5 grams of oxygen gas were used? What information from the question goes in letter A and explain why? What information from the question goes in letter H and explain why? What information from the question goes in letter G and explain why? 35.5 grams O 2 it’s the information given 35.5 grams O 2 _____g of Cr 2 O 3, that it the end label- what we are looking for g of Cr 2 O 3 _____g of Cr 2 O 3, it should match the end label g of Cr 2 O 3

8. ___Cr + ___O 2  ___Cr 2 O 3 243 a. How many grams of Chromium III oxide were produced if 35.5 grams of oxygen gas were used? What information from the question goes in letter F and explain why? What information from the question goes in letter B and explain why? What information from the question goes in letter C and explain why? 1 mole of Cr 2 O 3, it’s the mole to gram conversion 35.5 grams O 2 _____grams of O 2, it needs to be diagonal to the given. g of Cr 2 O 3 1 mole of O 2, it’s the mole gram conversion g of Cr 2 O 3 1 mole of Cr 2 O 3 g of O 2 1 mole of O 2

9. ___Cr + ___O 2  ___Cr 2 O 3 243 a. How many grams of Chromium III oxide were produced if 35.5 grams of oxygen gas were used? What information from the question goes in letter E and explain why? What information from the question goes in letter D and explain why? mole of Cr 2 O 3, it’s diagonal from 1 mole of Cr 2 O 3 35.5 grams O 2 mole of O 2, it’s diagonal from mole of O 2 g of Cr 2 O 3 1 mole of Cr 2 O 3 g of O 2 1 mole of O 2 mole of Cr 2 O 3 mole of O 2

10. NOW we plug in the numbers to find out our answer.

11. ___Cr + ___O 2  ___Cr 2 O 3 243 a. How many grams of Chromium III oxide were produced if 35.5 grams of oxygen gas were used? 35.5 grams O 2 g of Cr 2 O 3 151.989 g of Cr 2 O 3 1 mole of Cr 2 O 3 31.998 g of O 2 1 mole of O 2 2 mole of Cr 2 O 3 3 mole of O 2 35.5 X 2 X 151.989 31.998 X 3 10791.2 95.994 112 g of Cr 2 O 3

12. ___Cr + ___O 2  ___Cr 2 O 3 243 a. How many grams of Chromium III oxide were produced if 0.25 grams of oxygen gas were used? 0.25 grams O 2 g of Cr 2 O 3 151.989 g of Cr 2 O 3 1 mole of Cr 2 O 3 31.998 g of O 2 1 mole of O 2 2 mole of Cr 2 O 3 3 mole of O 2 0.25 X 2 X 151.989 31.998 X 3 75.995 95.994 0.79 g of Cr 2 O 3

13. ___Cr + ___O 2  ___Cr 2 O 3 243 b. How many grams of chromium metal were used if 75.0 grams of chromium III oxide were produced? 75.0 grams Cr 2 O 3 g of Cr 151.989 g of Cr 2 O 3 1 mole of Cr 2 O 3 51.996 g of Cr 1 mole of Cr 2 mole of Cr 2 O 3 4 mole of Cr 75.0 X 4 X 51.996 151.989 X 2 15598.8 303.978 51.3 g of Cr

14. ___Cr + ___O 2  ___Cr 2 O 3 243 c. How many grams of oxygen gas were used if 50.0 grams of chromium III oxide were produced? grams O 2 50.0 g of Cr 2 O 3 151.989 g of Cr 2 O 3 1 mole of Cr 2 O 3 31.998 g of O 2 1 mole of O 2 2 mole of Cr 2 O 3 3 mole of O 2 50.0 X 3 X 31.998 151.989 X 2 4799.7 303.978 15.8 g of O 2

15. ___Na + ___O 2  ___Na 2 O 24 a. How many grams of sodium are needed to make 500 grams of sodium oxide? grams Na 500 g of Na 2 O 61.979 g of Na 2 O 1 mole of Na 2 O 22.99 g of Na 1 mole of Na 2 mole of Na 2 O 4 mole of Na 500 X 4 X 22.99 61.979 X 2 459.80 123.958 371 g of Na

16. ___Na + ___O 2  ___Na 2 O 24 b. How many grams of oxygen are needed to react with 40.0 grams of sodium to complete this reaction? grams O 2 40.0 g of Na 22.99 of Na 1 mole of Na31.99 g of O 2 1 mole of O 2 4 mole of Na 1 mole of O 2 40.0 X 1 X 31.99 22.99 X 4 1279.92 91.96 13.9 g of O 2

17. ___Na + ___O 2  ___Na 2 O 24 c. If I had 300 grams of sodium how much sodium oxide can be made (assume there is an excess of oxygen gas) grams Na 2 O 300 g of Na 22.99 g of Na 1 mole of Na61.979 g of Na 2 O 1 mole of Na 2 O 4 mole of Na 2 mole of Na 2 O 300 X 2 X 61.99 22.99 X 4 37187.4 91.96 404 g of Na 2 O

18. ___Na + ___O 2  ___Na 2 O 24 c. How many grams of sodium oxide will be produced if we had 75.0 grams of sodium oxide? grams Na 2 O 75.0 g of Na 22.99 g of Na 1 mole of Na61.979 g of Na 2 O 1 mole of Na 2 O 4 mole of Na 2 mole of Na 2 O 75.0 X 2 X 61.99 22.99 X 4 9298.5 91.96 101 g of Na 2 O