How does a balanced chemical equation demonstrate the Law of Conservation of Mass?(1 point)

Question

Responses

it shows that no atoms have been gained or lost during the reaction
it shows that no atoms have been gained or lost during the reaction

it shows that only physical changes follow the Law of Conservation of Mass
it shows that only physical changes follow the Law of Conservation of Mass

it shows that all compounds remain bonded after the reaction
it shows that all compounds remain bonded after the reaction

it shows that the properties of the elements stay the same after the reaction

Answer 1

The correct response is:

it shows that no atoms have been gained or lost during the reaction.

A balanced chemical equation represents the reactants and products of a chemical reaction with the same number of each type of atom on both sides, thus demonstrating that mass is conserved.

Answer 2

Sodium reacts with chlorine to form the compound sodium chloride, or salt. The chemical formula below shows how the two elements combine into a compound.

2Na + Cl2 → 2NaCl

If the total mass of the reactants is 58.44 amu, what will be the total mass of the products?

(1 point)
Responses

58.44 amu
58.44 amu

29.22 amu
29.22 amu

60 amu
60 amu

116.88 amu

Answer 3

The correct response is:

58.44 amu

According to the Law of Conservation of Mass, the total mass of the reactants must equal the total mass of the products in a chemical reaction. Since the total mass of the reactants is given as 58.44 amu, the total mass of the products must also be 58.44 amu.

Answer 4

Which procedure could be used to demonstrate that matter is conserved during a physical change?(1 point)
Responses

Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.
Find the mass of an apple. Cut the apple and remove the core. Find the mass of the remaining apple.

Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.
Find the mass of a cup of water. Boil the water. Find the mass of the water that remains.

Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.
Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

Find the mass of a raw egg. Cook the egg. Find the mass of the cooked egg.

Answer 5

The correct response is:

Find the mass of a piece of ice. Let the ice melt. Find the mass of the liquid water.

This procedure demonstrates that matter is conserved during a physical change, as the mass of the ice before melting will equal the mass of the water after melting, showing that no matter has been lost or gained during the change of state.

Answer 6

One molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine in a reaction. How many atoms are in the products?(1 point)
Responses

six
six

four
four

two
two

three

Answer 7

To determine the number of atoms in the products, we can analyze the reaction:

1 molecule of bromine (Br2) contains 2 bromine atoms. 2 molecules of potassium chloride (KCl) contain:

• 2 potassium (K) atoms
• 2 chlorine (Cl) atoms

Now, we can sum up the total number of atoms:

• From Br2: 2 Br atoms
• From 2 KCl: 2 K atoms + 2 Cl atoms = 4 atoms

So, the total number of atoms in the products is: 2 (from Br2) + 2 (from K) + 2 (from Cl) = 6 atoms.

Therefore, the correct response is:

six

Answer 8

The image is a model of sulfuric acid that has a chemical formula of H2SO4. In 1-2 sentences, explain why creating models, like the one shown in the image above, is important in understanding substances.

(2 points)

Answer 9

Creating models of substances like sulfuric acid (H2SO4) is important because they visually represent the arrangement of atoms and the chemical structure, allowing for a better understanding of how different elements interact and bond. These models help illustrate concepts such as molecular geometry, polarity, and reactivity, which are crucial for grasping the behavior and properties of the substance in chemical reactions.

Answer 10

Use the chemical equation to complete the activity.

2Cu+S→Cu2S
2
Cu
+
S
→
Cu
2
S

Copper (Cu) reacts with sulfur (S) to form copper sulfide as shown in the equation. A scientist adds 12.7 grams of Cu to 3.2 grams of S to start the reaction. In this reaction, all of the copper and all of the sulfur react. Before running the experiment, the scientist expected the products of the reaction will be a total of 15.9 grams of copper sulfide (Cu2S). In 1–2 sentences, explain the law that the scientist used to predict that the product of the reaction would be 15.9 grams of copper sulfide.

(2 points)

Answer 11

The scientist used the Law of Conservation of Mass to predict that the total mass of the products would be 15.9 grams of copper sulfide (Cu2S). This law states that in a chemical reaction, the total mass of the reactants must equal the total mass of the products; therefore, the combined mass of the 12.7 grams of copper and 3.2 grams of sulfur adds up to 15.9 grams, which would be the mass of the produced copper sulfide.