Question

a digital balance reading of 101 grams
a small candle
a large glass jar with a tight fitting lid
a match

jamal places the candle on the balance, lights it, and quickly covers it with the glass jar.
after two minutes, he removes the jar and observes the candle burning inside the jar.
the general equation to represent this is:
hydrocarbon + o₂ → co₂ + h₂o + heat + light

jamal continues to monitor the mass reading on the balance throughout the experiment,
even after the candle flame has gone out (due to oxygen depletion).

what would jamal observe happening to the mass reading on the balance throughout the
experiment?
a the mass would decrease as the candle burns
b the mass would increase as the candle burns
c the mass would remain constant throughout the experiment
d the mass would fluctuate unpredictably

1. in the reaction na₂co₃ + 2hcl → 2nacl + h₂o + co₂, if the total mass of reactants is 108 grams,

what should the total mass of the products be?
a 108 grams
b 216 grams
c 54 grams
d 162 grams

1. given the reaction caco₃ → cao + co₂, if 100 grams of calcium carbonate decomposes, and

56 grams of calcium oxide is produced, what is the mass of the carbon dioxide produced?
a 56 grams
b 44 grams
c 100 grams
d 144 grams

1. when aluminum reacts with oxygen, aluminum oxide is formed. a student produces 204

grams of aluminum oxide.
4al + 3o₂ → 2al₂o₃

if the mass of oxygen used in the reaction was 96 grams, which of the following statements
are correct?
a the mass of aluminum used was 108 grams

Explanation:

Question 4

Step1: Recall the Law of Conservation of Mass

The Law of Conservation of Mass states that in a chemical reaction, the total mass of reactants is equal to the total mass of products. Mathematically, this can be expressed as:
$$\text{Mass of Reactants} = \text{Mass of Products}$$

Step2: Apply the Law to the Given Reaction

For the reaction $\ce{Na_{2}CO_{3} + 2HCl -> 2NaCl + H_{2}O + CO_{2}}$, the total mass of reactants is given as 108 grams. By the Law of Conservation of Mass, the total mass of products must be equal to the total mass of reactants.

Step1: Recall the Law of Conservation of Mass

The Law of Conservation of Mass states that the total mass of reactants equals the total mass of products in a chemical reaction. For the reaction $\ce{CaCO_{3} -> CaO + CO_{2}}$, we have:
$$\text{Mass of } \ce{CaCO_{3}} = \text{Mass of } \ce{CaO} + \text{Mass of } \ce{CO_{2}}$$

Step2: Solve for the Mass of $\ce{CO_{2}}$

Given:

• Mass of $\ce{CaCO_{3}}$ (reactant) = 100 grams
• Mass of $\ce{CaO}$ (product) = 56 grams

Substitute the known values into the equation:
$$100 = 56 + \text{Mass of } \ce{CO_{2}}$$

Solve for the mass of $\ce{CO_{2}}$:
$$\text{Mass of } \ce{CO_{2}} = 100 - 56 = 44 \text{ grams}$$

Step1: Recall the Law of Conservation of Mass

For the reaction $\ce{4Al + 3O_{2} -> 2Al_{2}O_{3}}$, the total mass of reactants (Al + $\ce{O_{2}}$) equals the total mass of products ($\ce{Al_{2}O_{3}}$).

Step2: Apply the Law to the Given Data

Given:

• Mass of $\ce{Al_{2}O_{3}}$ (product) = 204 grams
• Mass of $\ce{O_{2}}$ (reactant) = 96 grams (assumed from typical problems or visible context)

Let the mass of Al (reactant) be $m_{\ce{Al}}$. Then:
$$m_{\ce{Al}} + 96 = 204$$

Solve for $m_{\ce{Al}}$:
$$m_{\ce{Al}} = 204 - 96 = 108 \text{ grams}$$

Answer:

A. 108 grams

Question 5