1.
The process in which one or more substances change to make one or more new substances is called?
Correct Answer
B. Chemical reaction
Explanation
A chemical reaction refers to the process in which one or more substances undergo a transformation, resulting in the formation of new substances with different properties. This process involves the breaking and formation of chemical bonds between atoms, leading to a rearrangement of atoms and the creation of new chemical compounds. Chemical reactions can be observed through various observable changes such as color change, gas production, temperature change, or the formation of a precipitate.
2.
How can you tell when a chemical reaction is taking place? (check all that apply)
Correct Answer(s)
A. A gas forms
C. Energy is given off
D. There is a color change
Explanation
Reactions often have more than one sign. The more signs you see, the more likely a chemical reaction is taking place.
3.
The __________________________________________ says that mass cannot be created or destroyed.
Correct Answer(s)
law of conservation of mass
Explanation
The law of conservation of mass states that mass cannot be created or destroyed. This means that in any chemical reaction or physical process, the total mass of the substances involved remains constant. It implies that the total mass of reactants is equal to the total mass of products. This principle is a fundamental concept in chemistry and is based on the idea that matter is neither created nor destroyed, but only transformed or rearranged in a reaction.
4.
Is the chemical equation balanced? Na + Cl2 -------------------> NaCl
Correct Answer
B. No
Explanation
The chemical equation is not balanced because the number of atoms on both sides of the equation is not equal. On the left side, there is one Na atom, while on the right side, there is only one Cl atom. To balance the equation, we need to add a coefficient of 2 in front of NaCl, so that there are now 2 Cl atoms on the right side. This will result in a balanced equation: 2Na + Cl2 -> 2NaCl.
5.
Is the chemical equation balanced? 3Mg + N2 -------------> Mg3N2
Correct Answer
A. Yes
Explanation
The chemical equation is balanced because the number of atoms on both sides of the equation is equal. On the left side, there are 3 magnesium (Mg) atoms and 1 nitrogen (N) molecule (2 atoms). On the right side, there are 3 magnesium (Mg) atoms and 1 nitrogen (N) molecule (2 atoms) in the compound Mg3N2. Therefore, the equation is balanced.
6.
CO2(g) + H2O(l) → H2CO3(aq)
Correct Answer
A. Synthesis
Explanation
The given chemical equation represents the synthesis reaction. In a synthesis reaction, two or more reactants combine to form a single product. In this case, carbon dioxide gas (CO2) and water (H2O) react to form carbonic acid (H2CO3) in aqueous form. This reaction follows the general form of A + B → AB, where CO2 and H2O are the reactants and H2CO3 is the product. Therefore, the correct answer is synthesis.
7.
2 Na(s) + Cl2(g) → 2NaCl(s)
Correct Answer
A. Synthesis
Explanation
The given chemical equation represents the synthesis reaction, which involves the combination of two reactants to form a single product. In this case, two sodium atoms (Na) react with one molecule of chlorine gas (Cl2) to produce two molecules of sodium chloride (NaCl) as the product. Therefore, the correct answer is synthesis.
8.
Cl2(g) + 2NaBr(aq) → 2NaCl(aq) + Br2(l)
Correct Answer
C. Single displacement
Explanation
The given chemical equation represents a single displacement reaction. In this type of reaction, one element replaces another element in a compound. In this case, chlorine gas (Cl2) displaces bromine (Br) in sodium bromide (NaBr), resulting in the formation of sodium chloride (NaCl) and bromine liquid (Br2).
9.
2NaCl(l) → 2Na(s) + Cl2(g)
Correct Answer
B. Decomposition
Explanation
The given chemical equation shows the decomposition reaction of sodium chloride (NaCl) into sodium (Na) and chlorine gas (Cl2). In a decomposition reaction, a compound breaks down into its constituent elements or simpler compounds. Here, NaCl breaks down into Na and Cl2, indicating a decomposition reaction.
10.
Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)
Correct Answer
C. Single displacement
Explanation
In this reaction, zinc (Zn) reacts with hydrochloric acid (HCl) to form zinc chloride (ZnCl2) and hydrogen gas (H2). This is a single displacement reaction because zinc replaces hydrogen in the compound HCl to form ZnCl2.
11.
2KClO3(s) → 2KCl(s) + 3O2(g)
Correct Answer
B. Decomposition
Explanation
The given chemical equation represents a decomposition reaction. In a decomposition reaction, a compound breaks down into two or more simpler substances. In this case, 2KClO3(s) decomposes to form 2KCl(s) and 3O2(g). This reaction is a decomposition because a single compound (KClO3) is breaking down into two simpler substances (KCl and O2).
12.
CaCO3(s) → CaO(s) + CO2(g)
Correct Answer
B. Decomposition
Explanation
The given reaction involves the breakdown of calcium carbonate (CaCO3) into calcium oxide (CaO) and carbon dioxide (CO2). This is a decomposition reaction because a single compound is breaking down into two or more simpler substances. In this case, CaCO3 is decomposing into CaO and CO2.
13.
2Mg(s) + O2(g) → 2MgO(s)
Correct Answer
A. Synthesis
Explanation
The given chemical equation represents the reaction between magnesium (Mg) and oxygen (O2) to form magnesium oxide (MgO). This reaction is a synthesis reaction because two or more substances combine to form a single compound. In this case, two magnesium atoms combine with one oxygen molecule to form two molecules of magnesium oxide.
14.
Ba(NO3)2(aq) + K2SO4(aq) --> BaSO4(s) + 2KNO3(aq)
Correct Answer
D. Double displacement
Explanation
The given reaction involves the exchange of ions between two compounds. Ba(NO3)2 and K2SO4 react to form BaSO4 and 2KNO3. This type of reaction is known as a double displacement reaction because the positive and negative ions in the reactants switch places to form new compounds. In this case, the Ba2+ ion from Ba(NO3)2 combines with the SO42- ion from K2SO4 to form BaSO4, while the K+ ion from K2SO4 combines with the NO3- ion from Ba(NO3)2 to form KNO3.
15.
Fe(s) + CuSO4(aq) → FeSO4(aq) + Cu(s)
Correct Answer
C. Single displacement
Explanation
In this reaction, a single element (Fe) displaces another element (Cu) in a compound (CuSO4). This is known as a single displacement reaction, where one element is replaced by another element in a compound. The iron (Fe) reacts with the copper sulfate (CuSO4) to form iron sulfate (FeSO4) and solid copper (Cu). Therefore, the correct answer is single displacement.
16.
C(s) + O2(g) → CO2(g)
Correct Answer
A. Synthesis
Explanation
The given chemical equation represents the synthesis reaction, where a compound (C) combines with oxygen gas (O2) to form carbon dioxide gas (CO2). In a synthesis reaction, two or more substances combine to form a single compound. In this case, carbon (C) and oxygen (O2) combine to form carbon dioxide (CO2), making the answer "Synthesis" correct.
17.
2P(s) + 3Cl2(g) → 2PCl3(g)
Correct Answer
A. Synthesis
Explanation
The given chemical equation shows the combination of two reactants (2P(s) and 3Cl2(g)) to form a single product (2PCl3(g)). This is known as a synthesis reaction, where multiple reactants combine to form a single product. In this case, the synthesis reaction is between phosphorus (P) and chlorine gas (Cl2) to produce phosphorus trichloride (PCl3).
18.
H2SO4 → H2O(l) + SO3(g)
Correct Answer
B. Decomposition
Explanation
The given chemical equation shows the decomposition of H2SO4 into H2O(l) and SO3(g). Decomposition is a type of chemical reaction where a compound breaks down into simpler substances. In this case, H2SO4 breaks down into water (H2O) and sulfur trioxide (SO3).
19.
Ca(OH)2(s) → CaO(s) + H2O(g)
Correct Answer
B. Decomposition
Explanation
This reaction involves the breakdown of a compound, Ca(OH)2, into two separate compounds, CaO and H2O. This is known as decomposition, as the compound is being broken down into its individual components.
20.
3CuSO4 + 2 FeCl3 3CuCl2 + Fe2(SO4)3
Correct Answer
D. Double displacement
Explanation
The given chemical equation represents a double displacement reaction. In a double displacement reaction, the positive and negative ions of two compounds exchange places to form two new compounds. In this equation, CuSO4 and FeCl3 react to form CuCl2 and Fe2(SO4)3. The Cu2+ ion from CuSO4 combines with the Cl- ion from FeCl3 to form CuCl2, while the Fe3+ ion from FeCl3 combines with the SO4 2- ion from CuSO4 to form Fe2(SO4)3. Therefore, the correct answer is double displacement.
21.
The breaking down of a compound into simpler substances is
Correct Answer
C. Decomposition
Explanation
Decomposition refers to the process of breaking down a compound into simpler substances. This can occur through various means such as heat, light, or chemical reactions. During decomposition, the compound undergoes a chemical change and is transformed into its constituent elements or simpler compounds. This is the opposite of synthesis, where simpler substances combine to form a more complex compound. Displacement refers to the replacement of one element in a compound by another element, while endothermic refers to a reaction that absorbs heat.
22.
Which of the following types of reactions results in a single product?
Correct Answer
A. A synthesis reaction
Explanation
A synthesis reaction is a type of chemical reaction where two or more substances combine to form a single, more complex product. This reaction involves the combination of reactants to create a new compound, resulting in the formation of only one product. Therefore, a synthesis reaction is the correct answer as it is the only type of reaction listed that results in a single product.
23.
What coefficients would balance the following equation?Sr + H2O → Sr(OH)2 + H2
Correct Answer
C. 1, 2, 1, 1
Explanation
The given equation is Sr + H2O → Sr(OH)2 + H2. To balance the equation, we need to ensure that the number of atoms on both sides of the equation are equal. By assigning coefficients to each compound, we can balance the equation. In this case, the balanced equation is 1Sr + 2H2O → 1Sr(OH)2 + 1H2. Therefore, the correct answer is 1, 2, 1, 1.
24.
Which of the following is NOT an observable clue that a chemical reaction has occurred?
Correct Answer
D. Mixing two reactants
Explanation
Mixing two reactants is not an observable clue that a chemical reaction has occurred because simply mixing two substances does not necessarily result in a chemical reaction. In order for a chemical reaction to occur, there must be a change in the chemical composition of the substances involved, which is not evident just by mixing them together. Observable clues such as the release of a gas, odor change, and precipitate formation indicate chemical reactions because they demonstrate a transformation in the properties and composition of the substances involved.
25.
An insoluble substance formed from two solutions is a
Correct Answer
B. Precipitate
Explanation
When two solutions are mixed together, a precipitate may form if an insoluble substance is produced. A precipitate is a solid that forms from a chemical reaction between the two solutions. It is insoluble, meaning it does not dissolve in the solution. Therefore, the correct answer is "precipitate".