Which of the following equations shows a chemical change?(1 point)
Responses
NH3(g)→NH3(l)
N H 3, which is a gas right-arrow N H 3, which is a liquid
H2O(s)→H2O(g)
H 2 O, which is a solid right-arrow H 2 O, which is a gas
C2H5OH(l)→C2H5OH(g)
C 2 H 5 O H, which is a liquid right-arrow C 2 H 5 O H, which is a gas
C3H8+5O2→3CO2+4H2O
C3H8+5O2→3CO2+4H2O
The equation that shows a chemical change is C3H8 + 5O2 → 3CO2 + 4H2O.
The equation that shows a chemical change is the last one: C3H8+5O2→3CO2+4H2O.
To determine if a chemical change has occurred, you need to look for evidence of a chemical reaction. In this equation, you can see that C3H8 (propane) reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). The reactants (C3H8 and O2) are transformed into the products (CO2 and H2O), indicating a chemical change.
The other equations given involve phase changes (changes in state of matter) rather than chemical reactions. NH3(g) → NH3(l) shows the change from a gas to a liquid (condensation). H2O(s) → H2O(g) represents the change from a solid to a gas (sublimation). C2H5OH(l) → C2H5OH(g) shows the change from a liquid to a gas (evaporation). These phase changes do not involve the formation of new substances and, therefore, do not represent a chemical change.
How many atoms of carbon (C) are present in the reactants of the following chemical equation?
C7H16+O2→CO2+H2O
(1 point)
Responses
7 atoms
7 atoms
16 atoms
16 atoms
23 atoms
23 atoms
1 atom
There are 7 atoms of carbon (C) present in the reactants of the chemical equation.
In the reactant C7H16 (heptane), there are 7 carbon atoms.
Use the equation to answer the question.
CH4 + 2O2 → CO2 + 2H2O
If you change the 2 in front of 2O2
to a 3, what will be the change in the results on the right side of the equation?
(1 point)
Responses
There is an extra O2
molecule left over.
There is an extra cap o sub 2 molecule left over.
Nothing changes in the equation.
Nothing changes in the equation.
There are now 3H2O
molecules.
There are now 3 cap h sub 2 cap o molecules.
There are now 3CO2
molecules.
If you change the 2 in front of 2O2 to a 3, the change in the results on the right side of the equation is that there are now 3CO2 molecules.
According to the Law of Conservation of Mass, if 88 g of carbon dioxide ( CO2
) is produced in a reaction between oxygen (O) and 24 g of carbon (C), what is the mass of dioxygen ( O2
) in the reactants?(1 point)
Responses
24 g
24 g
32 g
32 g
104 g
104 g
64 g
64 g
To determine the mass of dioxygen (O2) in the reactants, we can use the balanced chemical equation and the Law of Conservation of Mass.
The balanced equation is:
C + O2 → CO2
From the equation, we can see that for every 1 mole of carbon (C), we need 1 mole of O2 to produce 1 mole of CO2.
The molar mass of CO2 is 44 g/mol.
So, to produce 88 g of CO2, we need 88 g/44 g/mol = 2 moles of CO2.
Since we need an equal amount of O2 to produce CO2, we also need 2 moles of O2.
The molar mass of O2 is 32 g/mol.
Therefore, the mass of O2 in the reactants is 2 moles * 32 g/mol = 64 g.
The correct answer is 64 g.
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
four
four
six
six
three
three
two
In the reaction where one molecule of bromine (Br2) and two molecules of potassium chloride (KCl) combine, two products are formed: two molecules of potassium bromide (KBr) and one molecule of chlorine gas (Cl2).
In KBr, there is one potassium atom (K) and one bromine atom (Br). Since there are two KBr molecules, there will be a total of 2 potassium atoms and 2 bromine atoms in the KBr product.
In Cl2, there are two chlorine atoms (Cl). Since there is one Cl2 molecule, there will be a total of 2 chlorine atoms in the Cl2 product.
Therefore, in the products, there are 2 potassium atoms + 2 bromine atoms + 2 chlorine atoms = 6 atoms.
The correct answer is six.
Use the unbalanced chemical equation to answer the question.
2NaHCO3 → Na2CO3 + CO2
Which of the following can be added to the products to balance the equation?
(1 point)
Responses
H2O
H 2 O
H2
H 2
O2
O 2
CH2OH
To balance the given chemical equation, we need to ensure that there is an equal number of atoms on each side. Let's examine the equation:
2NaHCO3 → Na2CO3 + CO2
On the left side, we have 2 sodium (Na) atoms, 2 hydrogen (H) atoms, 2 carbon (C) atoms, and 6 oxygen (O) atoms.
On the right side, we have 2 sodium (Na) atoms, 1 carbon (C) atom, and 5 oxygen (O) atoms.
To balance the equation, we need to add an equal number of atoms to the products.
Looking at the options provided, the only option that can be added to balance the equation is O2 (oxygen gas). Adding O2 will introduce additional oxygen atoms to the products and allow for the equation to be balanced.
Therefore, the correct answer is O2.
Acid-base reactions can also be classified as which type of reaction?(1 point)
Responses
synthesis
synthesis
decomposition
decomposition
single replacement
single replacement
double replacement
double replacement
Acid-base reactions can also be classified as double replacement reactions.
Which statement correctly compares synthesis and decomposition reactions?(1 point)
Responses
Synthesis and decomposition reactions are both neutralization reactions. Synthesis reactions are in the form A + B → AB, while decomposition reactions are in the form AB → A + B.
Synthesis and decomposition reactions are both neutralization reactions. Synthesis reactions are in the form A + B → AB, while decomposition reactions are in the form AB → A + B.
Synthesis and decomposition reactions are opposites of each other. Synthesis reactions are in the form A + B → AB, while decomposition reactions are in the form AB → A + B.
Synthesis and decomposition reactions are opposites of each other. Synthesis reactions are in the form A + B → AB, while decomposition reactions are in the form AB → A + B.
Synthesis and decomposition reactions are both neutralization reactions. Synthesis reactions are in the form AB → A + B, while decomposition reactions are in the form A + B → AB.
Synthesis and decomposition reactions are both neutralization reactions. Synthesis reactions are in the form AB → A + B, while decomposition reactions are in the form A + B → AB.
Synthesis and decomposition reactions are opposites of each other. Synthesis reactions are in the form AB → A + B, while decomposition reactions are in the form A + B → AB.
Synthesis and decomposition reactions are opposites of each other. Synthesis reactions are in the form A + B → AB, while decomposition reactions are in the form AB → A + B.
Aluminum oxide, Al2O3, decomposes into aluminum, Al, and oxygen gas, O2. Which ratio of aluminum to oxygen gas is in the products of the reaction?(1 point)
Responses
1:3
1:3
4:3
4:3
3:2
3:2
2:3
The ratio of aluminum to oxygen gas in the products of the reaction is 2:3.
The balanced equation for the decomposition of aluminum oxide (Al2O3) is:
2Al2O3 → 4Al + 3O2
From the equation, we can see that for every 2 moles of aluminum oxide, we get 4 moles of aluminum and 3 moles of oxygen gas. This means the ratio of aluminum to oxygen gas in the products is 4:3.
Therefore, the correct answer is 4:3.
The left side of a chemical reaction is shown.
Cu + AgNO3 →
Which type of reaction will the reactants undergo?
(1 point)
Responses
decomposition
decomposition
double displacement
double displacement
synthesis
synthesis
single displacement
The reactants Cu + AgNO3 will undergo a single displacement reaction.
In a single displacement reaction, one element replaces another element in a compound. In this case, the copper (Cu) will replace the silver (Ag) in silver nitrate (AgNO3), resulting in the formation of copper nitrate (Cu(NO3)2) and silver.
Therefore, the correct answer is single displacement.
Which phrase describes an oxidizing agent?(1 point)
Responses
a substance that provides oxygen in a reaction
a substance that provides oxygen in a reaction
a substance that gains an electron in a reaction
a substance that gains an electron in a reaction
a substance that reacts with oxygen
a substance that reacts with oxygen
a substance that provides electrons to other substances
An oxidizing agent is a substance that gains an electron in a reaction.
Which element is most likely to be reduced in a reaction?(1 point)
Responses
oxygen
oxygen
magnesium
magnesium
sodium
sodium
hydrogen
Hydrogen is the element most likely to be reduced in a reaction.
In a chemical reaction, reduction involves the gain of electrons. Hydrogen typically acts as an oxidizing agent, meaning it tends to lose electrons and be oxidized in a reaction. Therefore, in the context of an overall reaction, hydrogen is more likely to be reduced by accepting electrons from another species.
Therefore, the correct answer is hydrogen.