er E2420 the r , a c e connect Sa Chapter 3 Assignment 35 3 attempts let Check m

Question

er E2420 the r , a c e connect Sa Chapter 3 Assignment 35 3 attempts let Check my work Be sure to answer all parts. When powdered zinc is heated with sulfar, a violent reaction occurs, and zinc sulfide forms: points Zn(s)+S(s) ZnS) funbalanced (a) Some of the reactants also combine with oxygen in air to form zinc oxide and sulfur dioxie. When S3.2 g of Zn reacts with 52.4 g of S. 1049 g of ZnS forms. What is the percent yield of ZmS? References b) If all the remaining reactants combine with oxygen, how many grams of each of the two oxides form? Mass ZnO: Mass SO Prev 3S of 35 patients know that they can 20% discount if the account ull. This extends only through Please do no Observation bed and Inpatient Charts June

Explanation / Answer

a)

The balanced reaction is

8Zn + S8 = 8ZnS

83.2 g of Zn = 83.2 / 65.38 = 1.27 moles

52.4 g of S8 = 52.4 / 256.52 = 0.20 moles

1 mole Zn makes 1 mole ZnS

so 1.27 moles Zn will make 1.27 moles of ZnS weighing 1.27 x 97.445 = 124 grams

Percent yield = (Actual yield / theoretical yield) x 100

= (104.9 / 124 ) x 100

= 84.6 %

b)

104.9 grams of ZnS = 104.9/ 97.445 = 1.08 moles

1.08 moles of ZnS will utilise 1.08 moles of Zn weighing 1.08 x 65.38 = 70.38 grams .

So the amount of Zn left = 83.2 - 70.38 = 12.82 grams

Number of moles of S8 utilised will be (1/8) x 1.08 = 0.134 moles weighing 34.5 grams

So amount of S left = 52.4 - 34.5 = 17.9 grams

2Zn + O2 = 2ZnO

2 moles or 130.76 grams of Zn make 2 moles or 162.76 grams of ZnO

So 12.82 grams of Zn will make ( 12.82 x 162.76) / 130.76 = 15.96 grams of ZnO

Likewise

S + O2 = SO2

1 mole or 32.065 grams of S makes 1 mole or 64.06 grams of SO2

so 17.9 grams of S will make ( 17.9 x 64.06 ) / 32.065 = 35.76 grams of SO2

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