The equations of chemical reactions – one of the most important components of a course of chemistry in any educational institution. Interaction of acids with the bases are rather widespread task at the most different types of an examination – on independent and examinations and also during testing.
It is required to you
- - sulfuric and hydrochloric acids;
- - hydroxides of potassium and copper;
- - phenolphthalein.
Instruction
1. Acids represent complex substances, two-piece – atoms of hydrogen and the acid remains. Acids can be soluble in water and insoluble. Refer connections which also incorporate two parts – atoms of metals and hydroxyl groups to the bases. The number hydroksogroup will coincide with metal valency.
2. Chemical reactions between acid and the basis as a result of which salt and water are formed is called neutralization reaction. This chemical process is referred to exchange reaction in which acids and the bases exchange the components. Any can interact with soluble acids in water (both soluble, and insoluble in water) the bases.
3. Example No. 1. Write reaction of interaction of hydrochloric acid with potassium hydroxide. In the left member of equation write down the substances reacting: HCl + = Components of substances will exchange KOH the parts – to the place of atom of hydrogen there will be a metal atom – potassium. The released hydrogen will connect to hydroxyl group, forming at the same time a water molecule: HCl + KOH = KCl + H2O
4. Visually signs of reaction cannot be noticed as solutions of acid and the basis are transparent. However by practical consideration it is possible to prove that neutralization nevertheless happened. For this purpose pour 2 ml of potassium hydroxide in a test tube and place in it an indicator strip – phenolphthalein. In the alkaline environment it will change coloring for crimson at once. Flow in a test tube as much of hydrochloric acid and the indicator will become colourless. It demonstrates that there is no alkali left in a test tube any more, and there was a neutralization by its acid, that is salt and water were formed.
5. Example No. 2. Write the copper hydroxide interaction reaction equations with sulfuric acid. Freshly cooked hydroxide of copper represents insoluble substance of blue color in water. For carrying out reaction take 1 ml of a deposit and flow to it 2 ml of sulfuric acid. As a result of reaction the deposit will be dissolved, and the received solution will become blue color due to formation of sulfate of copper and water. To the place of hydrogen in acid there will be a copper atom, and hydrogen will connect to hydroksogruppy, forming a molecule of water.Cu (OH) 2 + H2SO4 = CuSO4 + 2H2O