GCSE · Chemistry · Edexcel · Spec 1CH0

General reactions of acids with metals, metal oxides, metal hydroxides and metal carbonates

Magnesium fizzes in acid; copper oxide doesn't make a single bubble. Same hidden rule underneath, though. Learn it and you can predict the products before anything happens.

Chemistry · Reactions of acids

Same acid, four different partners

Choose what the acid meets, then follow that route to see what it makes. Try all four.

4 possible routes.

On Hydrochloric acid + ?. 3 branches to choose from.

Hydrochloric acid is on every route here, so every salt ends in 'chloride'. The salt never goes away. The only thing that changes is what comes with it.

Watch out: Every route ends in a salt. If your answer to 'acid + something' has no salt in it, go back and look again.

Naming the salt

Metal first, acid second

Name the salt and complete each word equation. The first one is done for you; then it's your turn.

magnesium + hydrochloric acid → magnesium chloride + hydrogenThe metal gives the salt its first name: magnesium. The acid gives the ending, and each acid has its own: hydrochloric acid → chloride, sulfuric acid → sulfate, nitric acid → nitrate. And a metal with an acid gives hydrogen.
Next: nitric acid + zinc oxide. The metal is zinc, so the salt's name starts with 'zinc'.Your turn. Which ending does nitric acid give?
missing step

Which line is step 3?

Nitric acid gives the ending 'nitrate', so the salt is zinc nitrate.The salt is zinc chloride, just like the example above.The salt is zinc oxide, because that's what we started with.

Predict, then check

Picture four test tubes, each with dilute hydrochloric acid in it. Commit before you look.

You add magnesium to the first tube, copper to the second, copper carbonate to the third and copper oxide to the fourth. Which tubes fizz?

Where does the gas come from?

Whose hydrogen is it?

Magnesium is dropped into hydrochloric acid and bubbles of hydrogen stream off. The equation is Mg(s) + 2HCl(aq) → MgCl₂(aq) + H₂(g).

Where does the hydrogen in those bubbles come from? Pick the idea closest to what you think right now.

From the magnesium. It's the thing that fizzes, so the gas must be coming out of it.From the water. The acid is dilute, so there's lots of water to split up.A bit from each: the magnesium gives some and the acid gives the rest.From the acid. Its hydrogen ions end up as the hydrogen gas.

How sure are you?

I'm sureI think soI'm guessing

From the magnesium. It's the thing that fizzes, so the gas must be coming out of it.

This is a common misconception

It's a really natural thought, because the bubbles form on the metal. But look at the left-hand side of the equation: magnesium is just Mg. There's no H in it anywhere. The bubbles appear at the metal, but the hydrogen comes from the acid.

From the water. The acid is dilute, so there's lots of water to split up.

This is a common misconception

Clever thinking, but water isn't in the equation as a reactant. The only thing on the left carrying hydrogen is HCl. Every acid in this lesson has H at the front of its formula: HCl, H₂SO₄, HNO₃. That's the clue.

A bit from each: the magnesium gives some and the acid gives the rest.

This is a common misconception

A fair-sounding compromise, but it doesn't survive the equation. Magnesium has no hydrogen to give, so none of the H₂ can come from it. All of it comes from the acid.

From the acid. Its hydrogen ions end up as the hydrogen gas.

This matches the evidence

Exactly right. The hydrogen gas comes from the hydrogen ions of the acid. The magnesium ends up in the salt, magnesium chloride, and the acid's hydrogen is what bubbles off.

The metal ends up in the salt. The hydrogen gas comes from the acid's hydrogen ions.

Chemistry · Reaction balancer

From word equation to symbol equation

Tap + or − under each substance until every atom count matches on both sides. Then read the state symbols: (s) solid, (l) liquid, (g) gas, (aq) dissolved in water.

Reactants

ZnCO₃(s)

HCl(aq)

Products

ZnCl₂(aq)

H₂O(l)

CO₂(g)

C1→1✓

O3→3✓

Zn1→1✓

H1→2✗

Cl1→2✗

Conservation check: count atoms on both sides.Not yet.

Three products this time. Water is a liquid, so it's (l). Carbon dioxide is a gas, so it's (g). Watch the oxygen: three in the carbonate, shared out between the water and the carbon dioxide.

Tap + or − under each molecule to set its coefficient.

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

What you need to know

metal + acid → salt + hydrogen
metal oxide + acid → salt + water, and metal hydroxide + acid → salt + water
metal carbonate + acid → salt + water + carbon dioxide
Salt names: the metal first, then the acid's ending. Hydrochloric acid → chloride, sulfuric acid → sulfate, nitric acid → nitrate
Copper, silver, gold and platinum don't react with dilute acids
State symbols: (s) solid, (l) liquid, (g) gas, (aq) dissolved in water

The big picture

When an acid reacts with a metal, a metal oxide, a metal hydroxide or a metal carbonate, it always makes a salt. What else forms depends on the partner: hydrogen with a metal, water with a base (a metal oxide or hydroxide), and water plus carbon dioxide with a carbonate. The salt is named from the metal plus an ending set by the acid: chloride, sulfate or nitrate.

Key points

1All four reactions make a salt. The only thing that changes is the product that comes with it.

2A base reacts with an acid to make a salt and water only. This is neutralisation, and metal oxides and metal hydroxides are the two main types of base.

3Two of the reactions fizz, with a different gas each time: hydrogen from a metal, carbon dioxide from a carbonate.

4The hydrogen gas from a metal comes from the hydrogen ions of the acid, not from the metal.

5Whether a metal reacts depends on its reactivity and on the concentration of the acid. A reacting metal gives bubbles and a temperature rise, and it corrodes.

6In symbol equations the acids are (aq), hydrogen and carbon dioxide are (g), and water is (l).

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Worked example

Problem

Hydrochloric acid reacts with copper carbonate. Name the products and write the word equation.

⚠ Watch out

Writing hydrogen as a product when an acid reacts with a metal hydroxide. The name looks as if it's about hydrogen, but a hydroxide is a base, so it makes a salt and water with no gas at all.

🧠

Memory hook

Metal makes hydrogen. Base makes water. Carbonate is greedy: water AND carbon dioxide. And the salt turns up every single time.

✓

Check yourself

Cover the page. Iron is added to dilute hydrochloric acid. Name both products, say which of the four routes this is, and explain how you knew.

Flashcards

(13)

What do the reactions of an acid with a metal, a metal oxide, a metal hydroxide and a metal carbonate all produce?

A salt. Every one of them.

metal + acid → ?

salt + hydrogen

metal carbonate + acid → ?

salt + water + carbon dioxide

What is neutralisation?

A base reacting with an acid to make a salt and water only.

Name the two main types of base.

Metal oxides and metal hydroxides.

How do you build the name of a salt?

The metal's name first, then the ending that comes from the acid.

Which salt ending does each acid give?

Hydrochloric acid → chloride. Sulfuric acid → sulfate. Nitric acid → nitrate.

Which four metals don't react with dilute acids?

Copper, silver, gold and platinum.

What two things decide whether a metal reacts with an acid?

How reactive the metal is, and the concentration of the acid.

Three signs that a metal is reacting with an acid?

Effervescence (bubbles), a temperature rise, and the metal corroding.

Which two of the four reactions fizz, and what gas does each give off?

A metal gives off hydrogen. A carbonate gives off carbon dioxide.

Where does the hydrogen gas in a metal and acid reaction come from?

The hydrogen ions of the acid.

In these symbol equations, which state symbol goes with the acid, with each gas, and with water?

The acid is (aq). Hydrogen and carbon dioxide are (g). Water is (l).

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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Same acid, four different partners

Metal first, acid second

Whose hydrogen is it?

From word equation to symbol equation

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