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answer the question above wolk period. Models of lo You ma model con sheet con o

ID: 1075461 • Letter: A

Question

answer the question above

wolk period. Models of lo You ma model con sheet con of the me shows = structu PRELAB QUESTIONS These questions are due at the beginning of the laboratory period. 1. Assume you need three moles of zinc per mole of tungsten and per mole of molybdenum this experiment. Determine the mass of zinc required to react with 500 mg of Wo, and was 500 mg of Mo03. 2. What volume of 12.1 M HCI solution is required to prepare 0.100 L of a 3.00 M HCI solution? 3. Balance the following reaction for the formation of HWO). Zn(s) + H + WO; = HWO, + ?

Explanation / Answer

Ans 1 :

Number of moles of tungsten = 0.500 / 183.84 = 0.00272 mol

Number of moles of Mo = 0.500 / 95.94 = 0.0052 mol

So number of moles of Zn required for tungsten = 3 x 0.00272 = 0.00816 mol

and mass of Zn required = 0.00816 x 65.38 = 0.5335 grams

Likewise number of moles of Zn required for Mo = 3 x 0.0052 = 0.0156 mol

Mass of Zn required = 0.0156 x 65.38 = 1.02 grams

Ans 2 : Using the formula M1 V1 = M2 V2

where M is molarity and V is volume of the solution

Putting all the values we get :

12.1 x V = 3.00 x 0.100

V = 0.0248 L

Ans 3 :

The reaction can be balanced by carefully identifying the elements on both the sides. Then the number of elements on both the sides are noted down. Then each one of it balanced with respect to the other one.

So the balanced reaction will be :

Zn (s) + H+ + WO3 = HWO3 + Zn+