Question 1

What is a chemical equation?

Accepted Answer

A chemical equation is a shorthand notation for representing a chemical reaction. It shows the chemical formulas of the reactants and products and the symbols and conditions for the reaction. It is a way to communicate the details of a chemical reaction in a concise and accurate manner.

Question 2

What coefficient is needed in front of the O₂ molecule to balance the following equation? 2 $\mathrm { C } _ { 4 }$ $\mathrm { H } _ { 10 }$ (g)+ ________ $\mathrm { O } _ { 2 }$ (g)? 8 $\mathrm { CO } _ { 2 }$ (g)+ 10 $\mathrm { H } _ { 2 }$ O (l)

Accepted Answer

To balance the equation, start by balancing elements that appear in only one reactant and one product, usually leaving oxygen for last. The equation given is $2 \mathrm{C}_4\mathrm{H}_{10}$ + $x\mathrm{O}_2$ → $8\mathrm{CO}_2$ + $10\mathrm{H}_2\mathrm{O}$. Balancing carbon and hydrogen first, we see that the carbons and hydrogens are already balanced with 8 carbons on both sides (2 * 4 from $2\mathrm{C}_4\mathrm{H}_{10}$ and 8 from $8\mathrm{CO}_2$) and 20 hydrogens on both sides (2 * 10 from $2\mathrm{C}_4\mathrm{H}_{10}$ and 2 * 10 from $10\mathrm{H}_2\mathrm{O}$). Next, balance the oxygen atoms. There are 16 oxygens from the $8\mathrm{CO}_2$ and 10 from the $10\mathrm{H}_2\mathrm{O}$, totaling 26 oxygen atoms needed. Since each $\mathrm{O}_2$ molecule provides 2 oxygen atoms, you need 13 $\mathrm{O}_2$ molecules to provide the 26 oxygen atoms required. Therefore, the coefficient in front of $\mathrm{O}_2$ should be 13.

Question 3

Balance the following equation. ________ NO → ________ N₂O + ________ NO₂

Accepted Answer

The balanced equation is 3 NO → N2O + NO2, which corresponds to choice A (3,1,1).

Question 4

Steel wool wetted with vinegar is stuffed into a narrow mouth round glass bottle.A rubber balloon is then sealed over the mouth of the bottle.After several hours,the balloon inflates into the bottle in an inverted manner.What happened?

Accepted Answer

The vinegar reacts with the steel wool, causing a chemical reaction that absorbs oxygen from the air inside the bottle. This decreases the internal pressure, and the higher external atmospheric pressure pushes the balloon into the bottle, inflating it in an inverted manner.

Question 5

Given the following generic chemical reaction,which is the product? X → Y

Accepted Answer

The arrow is used to separate the reactants from the products. In this case, X is the reactant and Y is the product. Therefore, answer choice A is correct.

Question 6

-How many diatomic molecules are represented in the illustration above?

Accepted Answer

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Question 7

Which of the following is a correctly balanced equation?

Accepted Answer

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Question 8

-Which equation best describes the reaction represented in the illustration above?

Accepted Answer

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-Which equation best describes the reaction represented...

Question 9

Balance these equations. ________ $\mathrm { H } _ { 2 }$ (g)+ ________ $\mathrm { N } _ { 2 }$ (g)? ________ N $\mathrm { H } _ { 3 }$ (g)

Accepted Answer

The balanced equation is 3 $\mathrm{H}_2$ (g) + 1 $\mathrm{N}_2$ (g) → 2 $\mathrm{NH}_3$ (g). This ensures that there are 6 hydrogen atoms and 2 nitrogen atoms on both sides of the equation.

Question 10

A friend argues that if mass were really conserved he would never need to refill his gas tank.What explanation do you offer your friend?

Accepted Answer

The Law of Conservation of Mass states that mass cannot be created or destroyed in a chemical reaction. When gasoline burns in a car's engine, its atoms are not destroyed; they are rearranged to form exhaust gases (like carbon dioxide and water vapor), which are expelled from the car. This is why you need to refill your gas tank: the mass of the gasoline is converted into other substances, not destroyed.

Question 11

What is a chemical reaction?

Accepted Answer

A chemical reaction occurs when one or more new compounds are formed by rearranging atoms. This involves a chemical change where the original substances are transformed into new substances with different chemical properties.

Question 12

For the following balanced equation,which has the highest coefficient? 4 H₂ + 2 C → 2 CH₄

Accepted Answer

The highest coefficient in the given equation is 4, which is for H₂.

Question 13

Which equations are balanced? 
a)Mg (s)+ 2HCl (aq)? $\mathrm { MgCl } _ { 2 }$ (aq)+ $\mathrm { H } _ { 2 }$ (g)
b)3Al (s)+ 3 $\mathrm { Br } _ { 2 }$ (l)? $\mathrm { Al } _ { 2 }$ $\mathrm { Br } _ { 3 }$ (s)
c)2HgO (s)? 2 Hg (l)+ $\mathrm { O } _ { 2 }$ (g)

Accepted Answer

Equation "a" is balanced with 1 Mg, 2 H, and 2 Cl on both sides. Equation "c" is balanced with 2 Hg and 2 O atoms on both sides. Equation "b" is not balanced because the product should be $AlBr_6$ for the stoichiometry to match.

Question 14

What coefficients balance the following equation? ________ $\mathrm { P } _ { 4 }$ (s)+ ________ $\mathrm { H } _ { 2 }$ (g)? ________ P $\mathrm { H } _ { 3 }$ (g)

Accepted Answer

To balance the equation, start with phosphorus (P). There is 1 P4 on the left, meaning 4 P atoms, which matches with 4 PH3 molecules on the right (each containing 1 P), so the phosphorus atoms are balanced with 1 P4 and 4 PH3. Next, balance hydrogen (H). There are 4 PH3 molecules on the right, each with 3 H atoms, totaling 12 H atoms. To balance hydrogen, you need 6 H2 molecules on the left (since each H2 has 2 H atoms, and 6*2=12). Therefore, the balanced equation is P4 + 6H2 → 4PH3.

Question 15

Given the following generic chemical reaction,which is the reactant? X → Y

Accepted Answer

In a chemical reaction, the reactant(s) are the starting material(s) that undergo a chemical change to form product(s). In this reaction, X is the starting material and it is being converted to Y. Therefore, X is the reactant.

Question 16

For the following balanced reaction,which of the following is a solid? 2 Na(l)+ Cl₂(g)→ 2 NaCl(s)

Accepted Answer

In the balanced chemical equation, the reactants are liquid sodium (Na) and gaseous chlorine (Cl2). The product formed is solid sodium chloride (NaCl). Therefore, the best choice for a solid in this reaction is NaCl. The other options - Na, 2 Na, Cl2, and Cl - are either liquids or gases.

Question 17

Balance the following chemical equation. ________ N₂ + ________ H₂ → ________ NH₃

Accepted Answer

The balanced chemical equation is N2 + 3H2 → 2NH3, which corresponds to choice A (1,3,2).

Question 18

Steel wool wetted with vinegar is sealed within a balloon inflated with air.After several hours,what happens to the volume of the balloon?

Accepted Answer

The vinegar accelerates the rusting process of the steel wool, a chemical reaction that consumes oxygen from the air inside the balloon. As the oxygen is used up, the volume of the balloon decreases, causing it to deflate.

Question 19

What is wrong with the following depiction of a chemical reaction?

Accepted Answer

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Question 20

For the following balanced reaction,which of the following is a gas? 2 Na(l)+ Cl₂(g)→ 2 NaCl(s)

Accepted Answer

Cl₂ (chlorine gas) is the only gaseous reactant or product in the given reaction.

Quiz 17: How Chemicals React

What is a chemical equation?

What coefficient is needed in front of the O₂ molecule to balance the following equation? 2 $\mathrm { C } _ { 4 }$ $\mathrm { H } _ { 10 }$ (g) + ________ $\mathrm { O } _ { 2 }$ (g) ? 8 $\mathrm { CO } _ { 2 }$ (g) + 10 $\mathrm { H } _ { 2 }$ O (l)

Balance the following equation. NO → N₂O + NO₂

Steel wool wetted with vinegar is stuffed into a narrow mouth round glass bottle.A rubber balloon is then sealed over the mouth of the bottle.After several hours,the balloon inflates into the bottle in an inverted manner.What happened?

Given the following generic chemical reaction,which is the product? X → Y

-How many diatomic molecules are represented in the illustration above?

Which of the following is a correctly balanced equation?

Balance these equations. ________ $\mathrm { H } _ { 2 }$ (g) + ________ $\mathrm { N } _ { 2 }$ (g) ? ________ N $\mathrm { H } _ { 3 }$ (g)

A friend argues that if mass were really conserved he would never need to refill his gas tank.What explanation do you offer your friend?

What is a chemical reaction?

For the following balanced equation,which has the highest coefficient? 4 H₂ + 2 C → 2 CH₄

Which equations are balanced? a) Mg (s) + 2HCl (aq) ? $\mathrm { MgCl } _ { 2 }$ (aq) + $\mathrm { H } _ { 2 }$ (g) b) 3Al (s) + 3 $\mathrm { Br } _ { 2 }$ (l) ? $\mathrm { Al } _ { 2 }$ $\mathrm { Br } _ { 3 }$ (s) c) 2HgO (s) ? 2 Hg (l) + $\mathrm { O } _ { 2 }$ (g)

What coefficients balance the following equation? ________ $\mathrm { P } _ { 4 }$ (s) + ________ $\mathrm { H } _ { 2 }$ (g) ? ________ P $\mathrm { H } _ { 3 }$ (g)

Given the following generic chemical reaction,which is the reactant? X → Y

For the following balanced reaction,which of the following is a solid? 2 Na(l) + Cl₂(g) → 2 NaCl(s)

Balance the following chemical equation. N₂ + H₂ → NH₃

Steel wool wetted with vinegar is sealed within a balloon inflated with air.After several hours,what happens to the volume of the balloon?

What is wrong with the following depiction of a chemical reaction?

For the following balanced reaction,which of the following is a gas? 2 Na(l) + Cl₂(g) → 2 NaCl(s)

Quiz 17: How Chemicals React

What is a chemical equation?

What coefficient is needed in front of the O2 molecule to balance the following equation? 2 C4\mathrm { C } _ { 4 }C4​ H10\mathrm { H } _ { 10 }H10​ (g) + ________ O2\mathrm { O } _ { 2 }O2​ (g) ? 8 CO2\mathrm { CO } _ { 2 }CO2​ (g) + 10 H2\mathrm { H } _ { 2 }H2​ O (l)

Balance the following equation. ________ NO → ________ N2O + ________ NO2

Steel wool wetted with vinegar is stuffed into a narrow mouth round glass bottle.A rubber balloon is then sealed over the mouth of the bottle.After several hours,the balloon inflates into the bottle in an inverted manner.What happened?

Given the following generic chemical reaction,which is the product? X → Y

-How many diatomic molecules are represented in the illustration above?

Which of the following is a correctly balanced equation?

-Which equation best describes the reaction represented in the illustration above?

Balance these equations. ________ H2\mathrm { H } _ { 2 }H2​ (g) + ________ N2\mathrm { N } _ { 2 }N2​ (g) ? ________ N H3\mathrm { H } _ { 3 }H3​ (g)

A friend argues that if mass were really conserved he would never need to refill his gas tank.What explanation do you offer your friend?

What is a chemical reaction?

For the following balanced equation,which has the highest coefficient? 4 H2 + 2 C → 2 CH4

What coefficients balance the following equation? ________ P4\mathrm { P } _ { 4 }P4​ (s) + ________ H2\mathrm { H } _ { 2 }H2​ (g) ? ________ P H3\mathrm { H } _ { 3 }H3​ (g)

Given the following generic chemical reaction,which is the reactant? X → Y

For the following balanced reaction,which of the following is a solid? 2 Na(l) + Cl2(g) → 2 NaCl(s)

Balance the following chemical equation. ________ N2 + ________ H2 → ________ NH3

Steel wool wetted with vinegar is sealed within a balloon inflated with air.After several hours,what happens to the volume of the balloon?

What is wrong with the following depiction of a chemical reaction?

For the following balanced reaction,which of the following is a gas? 2 Na(l) + Cl2(g) → 2 NaCl(s)

What coefficient is needed in front of the O₂ molecule to balance the following equation? 2 $\mathrm { C } _ { 4 }$ $\mathrm { H } _ { 10 }$ (g) + ________ $\mathrm { O } _ { 2 }$ (g) ? 8 $\mathrm { CO } _ { 2 }$ (g) + 10 $\mathrm { H } _ { 2 }$ O (l)

Balance the following equation. NO → N₂O + NO₂

Balance these equations. ________ $\mathrm { H } _ { 2 }$ (g) + ________ $\mathrm { N } _ { 2 }$ (g) ? ________ N $\mathrm { H } _ { 3 }$ (g)

For the following balanced equation,which has the highest coefficient? 4 H₂ + 2 C → 2 CH₄

What coefficients balance the following equation? ________ $\mathrm { P } _ { 4 }$ (s) + ________ $\mathrm { H } _ { 2 }$ (g) ? ________ P $\mathrm { H } _ { 3 }$ (g)

For the following balanced reaction,which of the following is a solid? 2 Na(l) + Cl₂(g) → 2 NaCl(s)

Balance the following chemical equation. N₂ + H₂ → NH₃

For the following balanced reaction,which of the following is a gas? 2 Na(l) + Cl₂(g) → 2 NaCl(s)