Question 1

Which of the following best describes the appearance of iodine before it reacts with zinc in the synthesis of zinc iodide?

Accepted Answer

Gray, brittle solid

Question 2

During the reaction between zinc and iodine, what color change indicates that the reaction is over?

Accepted Answer

Brownish to clear

Question 3

Which element was completely used up in the reaction to synthesize zinc iodide, according to the experiment?

Accepted Answer

Iodine

Question 4

What type of reaction occurs when zinc reacts with iodine to form zinc iodide?

Accepted Answer

Exothermic

Question 5

Given the chemical equation $$Zn(s) + I_2$(s) \rightarrow $$ZnI_2$$(s)$$, what is the mole ratio of zinc to iodine in the reaction?

Accepted Answer

$$1:1$$

Question 6

If you start with 1.71 g of iodine ($$I_2$$), how many moles of iodine are present? (Molar mass of $$I_2 = 253.8$$ \ g/mol$$)

Accepted Answer

$$0.00674 \ mol$$

Question 7

A student wants to prepare 500 mg of zinc iodide ($$ZnI_2). $$How many moles of $$ZnI_2$$ does this represent? (Molar mass of $$ZnI_2 = 253.8$$ \ g/mol$$)

Accepted Answer

$$0.00197 \ mol$$

Question 8

Which of the following best explains why the mass of zinc iodide produced is similar to the sum of the masses of zinc and iodine used, according to the Law of Conservation of Mass?

Accepted Answer

No atoms are lost or gained; they are simply rearranged to form new compounds.

Question 9

If 1.79 g of zinc ($$Zn) is $$used in the reaction, how many moles of zinc does this represent? (Molar mass of $$Zn = 65.38 \ g/mol)$$

Accepted Answer

$$0.0274 \ mol$$

Question 10

After the reaction, the solution is rinsed to ensure all zinc oxide is trapped. What is the purpose of this step in the experiment?

Accepted Answer

To ensure complete reaction and accurate measurement of zinc iodide produced.

Question 11

If the mass of the dry zinc iodide product is 2.26 g, and the total mass of zinc and iodine used is 3.50 g, what could explain the difference in mass?

Accepted Answer

Experimental error such as loss of product during transfer or incomplete reaction.

Question 12

Which observation supports that iodine was completely used up in the reaction?

Accepted Answer

No gray/silver pebbles remained in the reaction mixture.

Question 13

What is the chemical formula for zinc iodide?

Accepted Answer

$$ZnI_2$$

Question 14

If you have 0.0274 mol of zinc and 0.00674 mol of iodine, which reactant is the limiting reagent?

Accepted Answer

Iodine

Question 15

Which of the following is a real-world application of the synthesis of zinc iodide?

Accepted Answer

Used in organic synthesis as a catalyst and in medical imaging agents.

Question 16

If the reaction is exothermic, what does this imply about the energy changes during the formation of zinc iodide?

Accepted Answer

Energy is released to the surroundings as heat.

Question 17

Calculate the mass of zinc required to produce 1.57 mol of zinc iodide. (Molar mass of $$Zn = 65.38 \ g/mol)$$

Accepted Answer

$$102.7 \ g$$

Question 18

Calculate the mass of iodine required to produce 1.57 mol of zinc iodide. (Molar mass of $$I_2 = 253.8$$ \ g/mol$$)

Accepted Answer

$$398.5 \ g$$

Question 19

Which of the following best describes the appearance of zinc before the reaction?

Accepted Answer

Gray/silver, tiny pebbles

Question 20

If the final color of dry zinc iodide is black, what could this indicate about the product?

Accepted Answer

Possible contamination or decomposition during drying.

Synthesis and Decomposition of Zinc Iodide: Concepts, Calculations, and Laboratory Applications

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