Question 1

Which of the following is NOT a common sign that a chemical reaction has occurred?

Accepted Answer

Dissolving sugar in water

Question 2

Which of the following best describes the law of conservation of mass as it applies to chemical reactions?

Accepted Answer

The total mass of reactants must equal the total mass of products

Question 3

Which of the following elements is DIATOMIC in its natural state?

Accepted Answer

Oxygen ($$O_2)$$

Question 4

What is the correct balanced equation for the combustion of butane ($$C_4H_{10}) in $$oxygen?

Accepted Answer

$$2C_4H_{10} + 13O_2 \rightarrow 8CO_2 + 10H_2O$$

Question 5

Which symbol in a chemical equation indicates that a substance is dissolved in water?

Accepted Answer

$$(aq)$$

Question 6

A student observes a yellow solid forming when two clear solutions are mixed. What is the best explanation for this observation?

Accepted Answer

A chemical reaction has occurred, producing a precipitate

Question 7

Balance the following equation: $$Al + $$CuCl_2$$ \rightarrow $$AlCl_3$$ + Cu$$

Accepted Answer

$$2Al + 3CuCl_2 \rightarrow 2AlCl_3 + 3Cu$$

Question 8

Which of the following best explains why chemical equations must be balanced?

Accepted Answer

To satisfy the law of conservation of mass

Question 9

What is the correct balanced equation for the reaction of hydrogen and oxygen to form water?

Accepted Answer

$$2H_2 + O_2$ \rightarrow 2H_2O$$

Question 10

Which of the following is a correct representation of the reaction between sodium sulfate and calcium nitrate to produce sodium nitrate and calcium sulfate?

Accepted Answer

$$Na_2SO_4 + Ca(NO_3$)_2 \rightarrow 2NaNO_3 + $$CaSO_4$$

Question 11

A student writes the following unbalanced equation for the reaction of sodium oxide with water: $$Na_2O + H_2O \rightarrow NaOH. $$What is the correct balanced equation?

Accepted Answer

$$Na_2O + H_2O \rightarrow 2NaOH$$

Question 12

Which of the following best describes a precipitate?

Accepted Answer

A solid that forms from a solution during a chemical reaction

Question 13

Which of the following is the correct balanced equation for the reaction: $$C_3H_8 + O_2$ \rightarrow CO_2$ + H_2O$$?

Accepted Answer

$$C_3H_8 + 5O_2 \rightarrow 3CO_2 + 4H_2O$$

Question 14

If 10 grams of hydrogen react completely with 80 grams of oxygen to form water, what is the total mass of water produced according to the law of conservation of mass?

Accepted Answer

90 grams

Question 15

Which of the following is a correct use of state symbols in a chemical equation?

Accepted Answer

$$2Na(s) + 2H_2O(l) \rightarrow 2NaOH(aq) + H_2$(g)$$

Question 16

Which of the following equations is balanced?

Accepted Answer

$$2Mg + O_2$ \rightarrow 2MgO$$

Question 17

A reaction produces a color change, gas bubbles, and heat. What can you conclude?

Accepted Answer

A chemical reaction has likely occurred

Question 18

Which of the following is the correct balanced equation for the reaction: $$C_2H_6O_2 + O_2$ \rightarrow CO_2$ + H_2O$$?

Accepted Answer

$$C_2H_6O_2 + 2O_2 \rightarrow 2CO_2 + 3H_2O$$

Chemical Reactions and Balancing Chemical Equations: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard