Unit 1 (1.3) vocabulary quiz

a substance that has a pH below 7; will increase the concentration of hydrogen ions in solution is an​ (a)  

• acid

• Base

• neutral

Answer explanation

The question is asking about a substance that has a pH below 7 and will increase the concentration of hydrogen ions in solution. In the context of acidity and alkalinity, a substance with a pH below 7 is considered an acid. Acids are known to increase the concentration of hydrogen ions in a solution. Therefore, the correct option is 'acid'.

Any substance having a pH between 7 to 14 on the pH scale is a base. Some commonly used bases are baking soda, soap, limewater, and bleach.​ (a)  

• base

• acid

• neutral

Answer explanation

The question states that any substance having a pH between 7 to 14 on the pH scale is a base. Then it gives examples of some commonly used bases like baking soda, soap, limewater, and bleach. Since the blank is after a list of bases, the correct answer is 'base'.

Some common ________ _______ are nails rusting and drinks fizzing (such as in Alka-Seltzer). Suppose you have made a volcano with baking soda and vinegar; the molecules in the vinegar react with the molecules in the baking soda to erupt as carbon dioxide gas releases.

Answer explanation

The fill in the blanks in the question are referring to processes like rusting, fizzing, or erupting as in a baking soda and vinegar volcano. These are all examples of chemical reactions, hence 'chemical reactions' is the correct answer. In these processes, substances change into new substances with different properties, which is the definition of a chemical reaction.

When writing chemical equations, ​ (a)   are used to indicate the number of molecules present. The ​ (b)   are also used to balance a chemical equation.

• coefficients

• subscript

• Elements

Answer explanation

In the context of the question, 'coefficients' is the correct answer. When writing chemical equations, coefficients are used to indicate the number of molecules present. They are also used to balance a chemical equation. Hence, the term 'coefficients' fills both the blanks correctly in the question.

A reaction in which a substance reacts with oxygen gas to produce carbon dioxide, water, and heat. A ________ reaction occurs when a substance is burned. To burn fuel and produce energy, oxygen gas is required.

Answer explanation

The question describes a process where a substance reacts with oxygen to produce carbon dioxide, water, and heat, which is the definition of a combustion reaction. Therefore, the correct answer is 'combustion'. This reaction is often associated with fire or heat generation, as in burning fuel to produce energy.

In a __________ reaction, a compound splits into two or more substances. In soda, carbonic acid splits into carbon dioxide, which produces a fizz, and water.

Answer explanation

The given question describes a reaction where a compound splits into two or more substances. This process is known as a 'decomposition' reaction. In the example of soda, carbonic acid decomposes into carbon dioxide and water, causing the fizz.

When copper carbonate precipitates from a copper sulfate solution a ​ (a)   reaction takes place: CuSO4(aq) +  Na2CO3(aq) → CuCO3(s) +  Na2SO4(aq) Most ionic compounds can be made from a ​ (b)   reaction.

• double displacement

• synthesis

• Single displacement

• combustion

• decomposition

Answer explanation

The reaction mentioned in the question is a double displacement reaction. Such reactions occur when the ions of two compounds are exchanged, forming new compounds. Here, CuSO4 and Na2CO3 exchange their ions, resulting in the formation of CuCO3 and Na2SO4. Therefore, the correct answer is 'double displacement'. Most ionic compounds can indeed be made from such reactions.

Hydrogen chloride (HCl) and sodium hydroxide (NaOH) undergo a ______ _______ reaction to yield table salt (NaCl) and water (H2O).

Answer explanation

The reaction between Hydrogen chloride (HCl) and sodium hydroxide (NaOH) is a double replacement reaction. In this type of reaction, the cations and anions of two different compounds switch places to form two new compounds, in this case, table salt (NaCl) and water (H2O). So, the correct answer is 'double replacement' or 'double-replacement'.

an ionic substance (H3O+) formed when a water molecule combines with a hydrogen ion is called ________ ___

Answer explanation

The question asks what an ionic substance (H3O+) formed when a water molecule combines with a hydrogen ion is called. The correct answer is 'hydronium ion'. This term refers to the hydronium ion H3O+, which is formed by the combination of a water molecule with a hydrogen ion.

When you boil a pot of water, you will notice the water evaporating and turning into steam. This change from liquid water to water vapor is a. _____ ______ The steam is still H2O, just like the liquid water; it has simply changed from a liquid to a gas. This is also true of melting ice, a _____ ______ from a solid to a liquid.

Answer explanation

The question describes the process of a substance changing from one state of matter to another, such as from liquid to gas, or solid to liquid. These changes in state of matter are known as 'phase changes'. Hence, the process of water turning into steam and ice melting are both examples of a 'phase change'.