Write a balanced chemical reaction for the reaction of zinc with iodine, assuming that zinc and iodine each exist as solid atoms. Iodine is I2 and Zn is Zn. Mass of empty beaker: 102.62503 g Mass of beaker with dry reagent: 103.82 g Describe the appearance of the zinc-iodine reaction product. Mass of the reaction product: ? Mass of zinc iodide reaction product: ? Mass of reactants: Mass of iodine reacted: 0.91035 g Mass of zinc reacted: 0.214 g Total mass of reactants (zinc iodine): ? Calculate the percentage difference between the mass of the product and the mass of the reactants: (Mass of product – Mass of reactants) / Mass of reactants * 100
The Correct Answer and Explanation is:
Balanced Chemical Reaction:
Zn (s) + I2(s)→ZnI2(s)\text{Zn (s) + I}_2 \text{(s)} \rightarrow \text{ZnI}_2 \text{(s)}Zn (s) + I2(s)→ZnI2(s)
Calculations:
1. Mass of beaker with dry reagent:
= 103.82 g
2. Mass of empty beaker:
= 102.62503 g
3. Mass of reaction product (ZnI₂):
= 103.82 g – 102.62503 g
= 1.19497 g
4. Mass of reactants:
Zinc = 0.214 g
Iodine = 0.91035 g
Total mass of reactants:
= 0.214 g + 0.91035 g
= 1.12435 g
5. Mass of zinc iodide reaction product:
= 1.19497 g
6. Percentage difference between product and reactants:(1.19497−1.124351.12435)×100=(0.070621.12435)×100≈6.28%\left( \frac{1.19497 – 1.12435}{1.12435} \right) \times 100 = \left( \frac{0.07062}{1.12435} \right) \times 100 \approx 6.28\%(1.124351.19497−1.12435)×100=(1.124350.07062)×100≈6.28%
Explanation
The reaction between zinc and iodine is a classic example of a synthesis reaction, where two elements combine to form a compound. In this case, solid zinc reacts directly with solid diatomic iodine to form zinc iodide (ZnI₂), a white crystalline ionic compound. The balanced chemical equation confirms that one atom of zinc combines with one molecule of iodine (I₂) to produce one formula unit of ZnI₂.
The mass of the product formed was 1.19497 g, calculated by subtracting the mass of the empty beaker from the mass of the beaker containing the dry reaction product. The total mass of the reactants was determined by summing the given values for zinc (0.214 g) and iodine (0.91035 g), giving a combined reactant mass of 1.12435 g.
To assess experimental accuracy, the percentage difference between the measured product mass and the expected total reactant mass was calculated. A value of approximately 6.28% was obtained. This positive difference suggests a slightly higher measured product mass compared to the theoretical value based on the sum of the starting materials. Possible explanations include incomplete drying of the product, residual solvent or moisture, or minor measurement inaccuracies.
The product of the reaction, zinc iodide, typically appears as a white or colorless crystalline solid. Its formation is usually accompanied by the fading of the dark violet color of iodine and the disappearance of metallic zinc. The reaction can sometimes emit heat and show a brief glow if initiated energetically, reflecting its exothermic nature.
