# Metal + dilute acid

> Salt and hydrogen gas


## Objectives

- State that an active metal and a dilute acid give a salt and hydrogen gas.
- Name the salt and balance the equation for a given metal and acid.

## 1. Properties of iron




## 2. What is the fizz?

Predict: which gas is in the bubbles?

- Chlorine
- Carbon dioxide
- Oxygen
- Hydrogen ✓

The bubbles are hydrogen gas, and it comes from the acid: zinc takes the place of the hydrogen in HCl, forming the salt zinc chloride, and the hydrogen leaves as $\ce{H2}$ gas.

[ar-EG] الفقاقيع دي hydrogen gas، وجاية من الـ acid: الـ zinc بياخد مكان الـ hydrogen في الـ HCl، فيتكوّن الـ salt اللي اسمه zinc chloride، والـ hydrogen يطلع على شكل $\ce{H2}$ gas.
## 3. Salt + hydrogen

The metal takes the place of the hydrogen in the acid. The hydrogen comes off as a gas. Only metals above hydrogen in the activity series do this. Copper does not. Pattern: active metal + dilute acid → salt + hydrogen.


## 4. Worked: magnesium + sulphuric acid

Salt name: the metal + the acid's ending. $\ce{H2SO4}$ gives sulphate: magnesium sulphate. Formula: Mg is +2 and $\ce{SO4}$ is −2, so $\ce{MgSO4}$. The gas is hydrogen, $\ce{H2}$. Check the atoms: 1 Mg, 2 H, 1 S, 4 O on each side. Now you: zinc + dilute sulphuric acid → zinc ___ + ___ gas.


## 5. Metal or metal oxide?

Metal + dilute acid salt + hydrogen: it fizzes Metal oxide + acid salt + water: no gas A metal and a dilute acid give a salt and water.


## 6. Your turn

Which pair gives a salt and hydrogen gas?

- Calcium oxide + dilute hydrochloric acid
- Copper + dilute hydrochloric acid
- Copper (II) oxide + dilute sulphuric acid
- Calcium + dilute hydrochloric acid ✓

Calcium and dilute hydrochloric acid give a salt (calcium chloride) and hydrogen gas, because calcium is above hydrogen in the activity series. Copper is below hydrogen, so it does not displace it from the dilute acid, and a metal oxide with an acid gives a salt and water, with no gas.

[ar-EG] الـ calcium مع الـ dilute hydrochloric acid بيدّوا salt (calcium chloride) و hydrogen gas، عشان الـ calcium فوق الـ hydrogen في الـ activity series. الـ copper تحت الـ hydrogen فمش بياخد مكانه في الـ dilute acid، والـ metal oxide مع الـ acid بيدّي salt و water من غير gas.
## 7. Summary

Active metal + dilute acid → salt + hydrogen gas. Only metals above hydrogen in the activity series react this way. Metal oxide + acid → salt + water, with no gas. Iron is above hydrogen. Next you will see which iron salt it gives with dilute acids. Can you explain why a metal gives hydrogen with a dilute acid, but its oxide gives water? The metal takes the place of the hydrogen in the acid, so the hydrogen comes off as a gas. In a metal oxide, the oxygen joins the acid's hydrogen and forms water, so no gas is given off.



Chapter: Transition Elements (https://yaani.ai/ar/learn/chemistry/chem-s3-en.ch1)
Source: https://yaani.ai/ar/lesson/chem-s3-en.lesson-acid.metal-acid-reaction