Which of the following

Question

equations shows a chemical
change? (1 point)
Rn → Po+α 219
86
215
84
H O(s) → H O(g) 2 2
C H OH(l) → C H
OH(g)
2 5 2 5
2H2+ O2 → 2H2O

Answer 1

A chemical change involves a transformation of substances into new substances with different properties. Among the equations you've provided, the one that represents a chemical change is:

2H₂ + O₂ → 2H₂O

This equation shows the reaction of hydrogen and oxygen gases to form water, which is a new substance.

The other equations involve physical changes (like phase changes) or radioactive decay (Rn → Po + α), but do not represent chemical reactions that create new substances.

Answer 2

How many atoms of carbon
(C) are present in the
reactants of the following
chemical equation?
2C H + 17O → 12CO +
10H O
(1 point)
6 10 2 2
2
16 atoms
1 atom
12 atoms
7 atoms

Answer 3

To determine the number of carbon atoms present in the reactants of the chemical equation:

\[ 2C_{6}H_{10} + 17O_{2} \rightarrow 12CO + 10H_{2}O \]

Let's analyze the reactants:

1. The molecule \( C_{6}H_{10} \) contains 6 carbon (C) atoms.
2. Since there are 2 \( C_{6}H_{10} \) in the equation, the total number of carbon atoms from this reactant is:

\[ 2 \times 6 = 12 \text{ carbon atoms} \]

Therefore, the total number of carbon atoms in the reactants is 12.

So the correct answer is 12 atoms.

Answer 4

The following equation does
not demonstrate the Law of
Conservation of Mass. How
can it be changed so that
the equation does
demonstrate this law?
4Fe + O → 2Fe O
(1 point)
2 2 3
On the product side,
put a 3 in front of O2
On the product side
take out the 2 in
front of Fe2O3
On the reactant side,
put a 3 in front of O2
On the product side,
put a 4 in front
of Fe2O3

Answer 5

To demonstrate the Law of Conservation of Mass, the number of atoms of each element must be equal on both sides of the equation.

The given equation is:

\[ 4Fe + O \rightarrow 2Fe_2O_3 \]

Let's analyze the current equation:

• Reactants:

  • 4 Fe
  • \( O \) (which we need to count properly; let’s say there is just \( O \), which represents O atoms in a component).

• Products:

  • \( 2Fe_2O_3 \) (this has 4 Fe and \( 3 \times 2 = 6 \) O atoms).

We need the reactants to have the same number of \( O \) atoms as the products.

To balance the oxygen, you can place a 3 in front of \( O_2 \) in the reactants, since \( O_2 \) contains 2 oxygen atoms:

So, when you add 3 in front of \( O_2 \), the equation becomes:

\[ 4Fe + 3O_2 \rightarrow 2Fe_2O_3 \]

Now, on the reactant side, we have \( 3 \times 2 = 6 \) O atoms, which matches the 6 O atoms on the product side (from \( 2Fe_2O_3 \)).

Thus, the correct answer is:

On the reactant side, put a 3 in front of O2.

Answer 6

According to the Law of
Conservation of Matter, what
happens to atoms during a
chemical reaction? (1 point)
Nothing; they stay the
same
The atoms in the
reactants rearrange to
form new substances.
More atoms are
produced to form new
substances
Atoms are converted
into energy during the
chemical reaction.

Answer 7

According to the Law of Conservation of Matter, during a chemical reaction, the atoms in the reactants rearrange to form new substances.

This means that the total number of atoms is conserved, and no atoms are created or destroyed; they only change their arrangements to form products.

So, the correct answer is:

The atoms in the reactants rearrange to form new substances.

Answer 8

According to the Law of
Conservation of Mass, if 98 g
of carbon dioxide (CO ) is
produced in a reaction
between oxygen (O) and 24 g
of carbon (C), what is the
mass of dioxygen (O ) in the
reactants? (1 point)
2
2
32 g
74 g
64 g
24 g

Answer 9

According to the Law of Conservation of Mass, the total mass of the reactants must equal the total mass of the products.

In this case, we are given that:

• The mass of carbon (C) in the reactants is 24 g.
• The mass of carbon dioxide (CO₂) produced (the products) is 98 g.

To find the mass of dioxygen (O₂) in the reactants, we can set up the following equation:

\[ \text{Mass of reactants} = \text{Mass of products} \]

\[ \text{Mass of C} + \text{Mass of O}_2 = \text{Mass of CO}_2 \]

Substituting in the known values:

\[ 24 g + \text{Mass of } O_2 = 98 g \]

Now, solve for the mass of dioxygen (O₂):

\[ \text{Mass of } O_2 = 98 g - 24 g = 74 g \]

So, the mass of dioxygen (O₂) in the reactants is 74 g.