Acids and Bases

Revision for science exam

What does the word "acid" come from?

From Latin acidus meaning sour.

What are the general properties of acids?

Sour, corrosive, react with bases, metals, carbonates, and change indicator color.

What gas is produced when acids react with metals?

Hydrogen gas.

What gas is produced when acids react with carbonates?

Carbon dioxide gas.

Name three everyday acids.

Hydrochloric acid (stomach acid), citric acid (in lemons), acetic acid (vinegar).

What is the fundamental property of an acid?

Acids donate H⁺ ions.

What are bases that dissolve in water called?

Alkalis.

What happens when an acid reacts with a base?

They neutralize each other to form salt + water.

What is the fundamental property of bases?

Bases accept H⁺ ions.

Example of a base used in oven cleaners?

Sodium hydroxide (NaOH).

What color does blue litmus turn in acid?

Red.

What color does red litmus turn in a base?

Blue.

What color is phenolphthalein in a base?

Pink.

What color is methyl orange in acid?

Red.

What is pH 7?

Neutral.

What does pH < 7 indicate?

Acidic.

What does pH > 7 indicate?

Basic.

How much stronger is a solution with pH 3 than one with pH 6?

1000 times more H⁺ ions.

General reaction: metal + acid → ?

Salt + hydrogen.

General reaction: carbonate + acid → ?

Salt + carbon dioxide + water.

Acid + base (hydroxide) → ?

Salt + water.

Acid + hydrogen carbonate → ?

Salt + carbon dioxide + water.

What type of salts do hydrochloric, sulfuric, and nitric acids form?

Chlorides, sulfates, and nitrates.

What is an exothermic reaction?

A reaction that releases heat (feels hot).

Example of an exothermic reaction?

Combustion, respiration.

What is an endothermic reaction?

A reaction that absorbs heat (feels cold).

Example of an endothermic reaction?

Photosynthesis, baking a cake.

What is the pH of acid rain?

Less than 5.6.

What gases cause acid rain?

Sulfur oxides and nitrogen oxides.

What are natural sources of nitrogen oxides?

Lightning, volcanoes, bacteria.

What are man-made sources of sulfur oxides?

Burning fossil fuels, roasting sulfide ores.

Effects of acid rain on buildings?

Erodes limestone/sandstone and weakens metal.

How can acid rain be prevented?

Reduce emissions, use scrubbers, catalytic converters, burn fewer fossil fuels.

How can acidified water be corrected?

Add lime (CaO) to neutralize.