Stoichiometry Extra Practice Questions

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Fall 2017

Stoichiometry Extra Practice Questions 1. 2. 3. 4. 5. 6.

How many atoms are in 200 kg of CH4? If two moles of a material produces 24 g of material, what is your material? If you have 400 moles of cats, how many cats do you have? What is the mass percentage of S in H2SO4? What is the mass percentage of P in P4O10? Balance the following reactions: a. C6H6 + O2 ----> H2O + CO2 b. H2 + N2 ----> NH3 c. Fe + O2 ----> Fe2O3 d. Pb(OH)4 + H2SO4 ----> Pb(SO4)2 + H2O

7. A) Billy performed the following reaction, starting with 40 kg of Ca(OH)2. Ca(OH)2 + HCl ---> CaCl2 + H2O Billy isn’t too sure if the reaction is balanced. Can you help him out? B) Billy wants to know how many moles of CaCl2 should be produced. Can you help him? C) Billy’s reaction produced 5 g of CaCl2. What was the percent yield of this reaction?

8. For the following multistep reaction, what is the overall reaction equation? Make sure to balance the equations Cu + S + O2 ----> CuSO4 Zn + CuSO4 -----> ZnSO4 + Cu ZnSO4 + NaOH ----> H2SO4 + ZnO + Na

9. A) Sara plans to mix together Pb(NO3)2 and KI in order to produce PBI2 and KNO3. Please writeout the balanced chemical equation for her reaction. B) Sara’s lab does not allow her to use Pb based materials whose mass % exceeds 90 % Pb. Can she go forward with this reaction given the labs policy? © Copyright 2017 by Wizedemy Inc. All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, or sorted in a data base or retrieval system, without the prior written permission Wizedemy Inc.

Fall 2017 C) Sara adds 4 g of Pb(NO3)3 and 4.5 g of KI. Which of these two is the limiting reagent? D) Based on the amounts in part C, predict the theoretical yield of PbI2 in the reaction. E) If 2 g of PbI2 are recovered after the reaction, what is the percent yield of the reaction?

10. A) If 5 kg of Na2CO3 is mixed with 8000000 mg of HCl and the following reaction occurs, which is in excess and which is the limiting reagent? Na2CO3 + HCl ----> H2O + NaCl + CO2 B) The CO2 from the previous reaction was collected by plants in the lab and underwent photosynthesis, which is carried out via the following reaction scheme: 6CO2 + 6 H2O ----> C6H12O6 + 6O2 Given the amounts in B, determine how much sugar (C6H12O6) should be produced. C) What is the overall reaction equation for the previous multi-step reaction? D) If 500 g of sugar are produced, what is the percent yield of the reaction? 11. A) On a recent expedition to mars, the Mars rover designated Spirit collected several samples from the planets surface. One sample was found to contain 34.97 g of iron and 15.03 g of oxygen. What is the empirical formula of this Martian sample? B) In order to further study the sample, the Spirit rover mixed the iron oxide sample with aluminum to produce thermite, allowing for the measurement of the heat produced in this exothermic reaction. Balance the reaction for the thermite reaction. Fe2O3 + Al ----> Fe + Al2O3 C) To perform this reaction, the 50 g sample of iron oxide collected from the surface was mixed with 65 g of Al. Which of these reagents is in excess, and which is the limiting reagent? D) If the reaction results in 2 g of Al2O3, what is the percent yield of the reaction?

© Copyright 2017 by Wizedemy Inc. All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, or sorted in a data base or retrieval system, without the prior written permission Wizedemy Inc.

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