Question

1. what type of chemical reaction took place when you mixed lead (ii) nitrate and potassium iodide? (hint: consider the known reactants. what kind of compounds are they?) 3. write a skeletal chemical equation of the reaction of lead (ii) nitrate with potassium iodide, then balance it. 4. what was the sum of the masses of lead (ii) nitrate and potassium iodide? 5. how did the sum of the masses of lead (ii) nitrate and potassium iodide compare to the mass after the chemical reaction? were the masses equal or different? (there may be slight inaccuracies due to the limitations of the scale and slight differences in the beakers themselves) 6. is your answer to 5. supported by the law of conservation of mass? explain. 7. when you mixed acetic acid and sodium bicarbonate, what was the evidence of a chemical change? 8. what type of chemical reaction took place when you mixed acetic acid and sodium bicarbonate? 9. fill in the blanks to complete the chemical equation below: hc₂h₃o₂ + nahco₃ → ____ + h₂o + co₂(g) 10. what was the sum of the masses of acetic acid and sodium bicarbonate? 11. how did the sum of the masses acetic acid and sodium bicarbonate compare to the mass after the chemical reaction? were the masses equal or different? 12. is your answer to 11. supported by the law of conservation of mass? if not, discuss whether there was some issue with the experimental design. (hint: refer to your answer to 7. and the chemical equation from 9.)

Explanation:

Step1: Identify reaction type for lead (II) nitrate and potassium iodide

It is a double - displacement reaction as the cations and anions of the two reactants exchange places.

Step2: Write skeletal equation for lead (II) nitrate and potassium iodide

$Pb(NO_3)_2+KI
ightarrow PbI_2 + KNO_3$

Step3: Balance the equation for lead (II) nitrate and potassium iodide

$Pb(NO_3)_2 + 2KI
ightarrow PbI_2+2KNO_3$

Step4: For acetic acid and sodium bicarbonate reaction evidence

The evidence of a chemical change is the production of gas (bubbling), which is carbon dioxide.

Step5: Identify reaction type for acetic acid and sodium bicarbonate

It is an acid - base reaction (specifically a reaction between an acid and a carbonate - hydrogen carbonate compound) that also results in gas evolution.

Step6: Complete the acetic acid and sodium bicarbonate equation

$HC_2H_3O_2+NaHCO_3
ightarrow NaC_2H_3O_2 + H_2O+CO_2$

Step7: Regarding mass comparison and conservation of mass

According to the law of conservation of mass, in a closed system, the sum of the masses of reactants should equal the sum of the masses of products. However, if the reaction is not in a closed system and gas is evolved (like in the acetic acid - sodium bicarbonate reaction), the mass after the reaction will be less as the gas escapes.

Answer:

1. Double - displacement reaction for lead (II) nitrate and potassium iodide.
2. $Pb(NO_3)_2+KI

ightarrow PbI_2 + KNO_3$ (skeletal), $Pb(NO_3)_2 + 2KI
ightarrow PbI_2+2KNO_3$ (balanced).

1. Evidence of chemical change for acetic acid and sodium bicarbonate is gas production.
2. Acid - base reaction for acetic acid and sodium bicarbonate.
3. $NaC_2H_3O_2$ for the blank in the acetic acid and sodium bicarbonate equation.
4. In a closed system, mass of reactants = mass of products according to law of conservation of mass; in non - closed system with gas evolution (e.g., acetic acid and sodium bicarbonate), mass of products < mass of reactants due to gas escape.