Chemical Reactions Quick Check
1 of 51 of 5 Items
Question
Use the chemical reaction to answer the question.
CaCO3→CO2+CaO
A scientist heats 30 grams of calcium carbonate (CaCO3
) in the chemical reaction shown. What is the total mass of the products?
(1 point)
Responses
60 grams
60 grams
30 grams
30 grams
10 grams
10 grams
15 grams
15 grams
Chemical Reactions Quick Check
2 of 52 of 5 Items
Question
Use the chemical reaction to answer the question.
4Fe+3O2→2Fe2O3
What happens to atoms of Fe and O2 during the reaction?
(1 point)
Responses
They gain mass.
They gain mass.
They are rearranged.
They are rearranged.
They maintain their properties.
They maintain their properties.
They are lost.
The correct answer is:
They are rearranged.
Chemical Reactions Quick Check
3 of 53 of 5 Items
Question
Which is most likely to occur during a chemical reaction?(1 point)
Responses
New atoms are created.
New atoms are created.
Atoms of the original substance are lost.
Atoms of the original substance are lost.
Mass is conserved.
Mass is conserved.
The original substance maintains its properties.
The correct answer is:
Mass is conserved.
Chemical Reactions Quick Check
4 of 54 of 5 Items
Question
Use the chemical reaction to answer the question.
NaHCO3+HC2H3O2→NaC2H3O2+H2O+CO2
A student mixes baking soda (NaHCO3
) and acetic acid (HC2H3O2
) to produce a chemical reaction shown. Which statement about the reaction is correct?
(1 point)
Responses
Some atoms gain mass after the reaction.
Some atoms gain mass after the reaction.
The atoms of the reactants are regrouped during the reaction.
The atoms of the reactants are regrouped during the reaction.
There are more H atoms after the reaction.
There are more H atoms after the reaction.
Atoms of Na are destroyed during the reaction.
Atoms of Na are destroyed during the reaction.
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The correct answer is:
The atoms of the reactants are regrouped during the reaction.
Chemical Reactions Quick Check
5 of 55 of 5 Items
Question
Use the chemical reaction to answer the question.
2H2+O2→2H2O
There are four atoms of hydrogen (H
) before the reaction. How many atoms of hydrogen are present after the reaction?
(1 point)
Responses
4
4
5
5
8
8
2
The correct answer is:
4
To answer this question, we need to understand the concept of the Law of Conservation of Mass in chemical reactions. According to this law, in a chemical reaction, the mass of the reactants must be equal to the mass of the products.
The given chemical reaction is:
CaCO3 → CO2 + CaO
This reaction shows that calcium carbonate (CaCO3) decomposes and forms carbon dioxide (CO2) and calcium oxide (CaO) as products.
To find the total mass of the products, we need to calculate the individual masses of carbon dioxide and calcium oxide, and then add them together.
Looking at the reaction equation, we see that the molar mass of CaCO3 is 100.1 g/mol. Since we have 30 grams of CaCO3, we can calculate the number of moles by dividing the given mass by the molar mass:
30 g CaCO3 / 100.1 g/mol = 0.2997 mol CaCO3 (approximated to four decimal places)
Now, in the balanced chemical equation, we see that the molar ratio between CaCO3 and CO2 is 1:1. This means that for every mole of CaCO3, we generate one mole of CO2.
So, the number of moles of CO2 formed is also approximately 0.2997.
The molar mass of CO2 is 44.01 g/mol. We can calculate the mass of CO2 by multiplying the number of moles by the molar mass:
0.2997 mol CO2 * 44.01 g/mol = 13.18 g CO2 (approximated to two decimal places)
Similarly, for calcium oxide (CaO), the molar ratio between CaCO3 and CaO is also 1:1.
So, the number of moles of CaO formed is approximately 0.2997.
The molar mass of CaO is 56.08 g/mol. We can calculate the mass of CaO by multiplying the number of moles by the molar mass:
0.2997 mol CaO * 56.08 g/mol = 16.81 g CaO (approximated to two decimal places)
Finally, to find the total mass of the products, we add the masses of carbon dioxide and calcium oxide:
13.18 g CO2 + 16.81 g CaO = 29.99 g (approximated to two decimal places)
Therefore, the total mass of the products in this chemical reaction is approximately 29.99 grams.
The correct answer is:
60 grams