Chemistry 9 Lesson 3: Chemical properties of acids
1. Theoretical Summary
1.1. Chemical properties
- Acids discolor the color indicator
Acid solution turns blue litmus red.
- Acids react with metals:
Fe + 2HCl → FeCl2 + FRIENDS2
Fe + H2SO4 → FeSO4 + FRIENDS2
Acid solutions react with some metals to form salts and release H . gas2 (except Cu, Ag, Au)
HNO solution3, H2SO4 It reacts with many metals but does not release H .2
- Acid reacts with base
Acids react with bases to form salts and water
Cu(OH)2 + FRIENDS2SO4 → CuSO4 + 2 HOUSES2O
- Acids react with basic oxides
Acids react with basic oxides to form salts and water.
Fe2O3 + 6HCl → 2FeCl2 + 3 HOURS2O
1.2. Strong acid, weak acid
2. Illustrated example
2.1. Form 1: Write a chemical equation for the properties of acids
There are the following substances: CuO, Mg, Al2O3, Fe(OH)3, Fe2O3. Choose one of the given substances that react with HCl solution to produce:
a) The gas is lighter than air and flammable in air.
b) The solution is blue.
c) The solution is yellow-brown.
d) The solution is colorless.
Write the chemical equations.
a. A gas that is lighter than air and flammable in air is H2.
Mg + 2HCl → MgCl2 + FRIENDS2↑
b. The blue color solution is CuCl . solution2.
CuO + 2HCl → CuCl2 + FRIENDS2O
c. The yellow-brown solution is FeCl . solution3.
Fe(OH)3 + 3HCl → FeCl3 + 3 HOURS2O
Or Fe2O3 + 6HCl → 2FeCl3 + 3 HOURS2O
d. Colorless solutions are MgCl . solutions2, AlCl3.
Al2O3 + 6HCl → 2AlCl3 + 3 HOURS2O
Mg + 2HCl → MgCl2 + FRIENDS2↑
2.2. Form 2: Determine the formula of chemistry
Question 1: Give 32g of a trivalent metal oxide completely dissolved in 294g of H . solution2SO4. Find the formula for the metal oxide above.
The formula to find has the form: X2O3
– Volume H2SO4: m = 20.294100 = 58.8 g
– Number of moles H2SO4 = 0.6 mol.
– Reaction Equation:
X2O3 + 3 HOURS2SO4 → X2(SO)4)3 + 3 HOURS2O
0.2 mol 0.6mol
Molecular mass of oxide: M = 160.
So that oxide is Fe2O3.
Verse 2: Find the chemical formula of an acid with the following mass composition:
H: 2.1%; N: 29.8%; O: 68.1%.
Let the chemical formula of the acid be HxWOMENyOz. We have:
x : y : z = 2.1 : 2.1 : 4.2 = 1 : 1 : 2
→ The chemical formula of the acid is HNO2 (nitrous acid).
2.3. Form 3: Exercises about salt carbonates and hydrocarbons reacting with acids
a. Slowly add solution X containing x moles of HCl to solution Y containing y moles of Na .2HAVE3 (x < 2y), then a solution of Z containing V liters of gas is obtained. Calculate V?
b. If solution Y is added to solution X, solutions A and V . are obtainedfirst liters of gas. The reactions are complete and the gas volume is measured at standard conditions. Find the relationship between VUfirst with x, y.
a. Slowly add HCl to Na2HAVE3, the reaction takes place as follows:
HCl + Na2HAVE3 → NaHCO3 + NaCl (1)
But according to the beginning of the article, there is gas coming out, so the reaction continues:
HCl + NaHCO3 → NaCl + CO2 + FRIENDS2O (2)
Reaction (1) will proceed completely, yielding y moles of NaHCO3.
For reaction (2) to occur, then x > y.
Since the problem gives x < 2y, (2) react according to the number of moles of HCl remaining.
So V = 22.4.(x – y)
b. When giving Na2HAVE3 into HCl:
Na2HAVE3 + 2HCl → 2NaCl + CO2 + FRIENDS2O
1 mol 2 mol
y mol x mol
The problem gives x < 2y, so we calculate the number of moles of gas produced according to HCl:
DRAWfirst = x / 2 . 22.4
3.1. Essay exercises
Question 1: There are the following oxides: Fe2O3, SO2, CuO, MgO, CO2.
a) Which oxides react with H . solution?2SO4?
b) Which oxides react with NaOH solution?
c) Which oxides can react with H .?2O?
Write chemical equations.
Verse 2: Find the chemical formulas of acids with the following mass composition:
a) H: 2.4%; S : 39.1%; O: 58.5%.
b) H: 3.7%; P: 37.8%; O: 58.5%.
Question 3: Solution X contains a mole of HCl, solution Y contains b mole of Na .2HAVE3 (a < 2b)
a) If X is added very slowly to Y, then V . is obtainedfirst liters of gas.
b) Put Y in X, get V2 liters of gas.
Formula for calculating Vfirst, VOICE2 according to a, b
3.2. Multiple choice exercises
Question 1: H solution2SO4 Which substance reacts to produce hydrogen gas?
Verse 2: Which chemical property is not an acid?
A. React with metal
B. Effect with salt
C. React with acid oxide
D. React with basic oxides
Question 3: The solution reacts with CuO to give a product that is a blue solution:
A. NaOH . solution
B. Na . solution2HAVE3
C. HCl solution
D. Ca(OH) solution2
Question 4: A series of metals that react with H . solutions2SO4 dilution is:
A. Fe, Cu, Mg
B. Zn, Fe, Cu
C. Zn, Fe, Al.
D. Fe, Zn, Ag
Question 5: The group of substances that react with water and with HCl solution are:
A. Na2O, SO3 , HAVE2
B. KY2O, P2O5, High
C. Bao, SO3, P2O5
D. CaO, BaO, Na2O
The content of the lesson is summarized as follows: