Acids Bases and Salts Flashcards
What is the name of the scale which decides which substances are acids and alkali?
pH
What number is neutral on the pH scale
7
What side of the pH scale are alkalis?
Under 7
What do acid solutions contain?
H+ ions
What do alkali solutions contain?
OH- ions
How is the concentration of ions measured?
mol/dm cubed
What are H+ ions in
Water
What concentration of OH- ions do strong alkalis have?
A high one - weak alkalis have a low one
What degree of ionisation do strong acids and alkalis have?
A high one
Why is hydrochloric acid a strong acid?
Because when the HCl molecules dissolve in the water almost all of the hydrogen atoms form H+ ions (ionisation)
Why is ethanoic acid a weak acid?
Because only about 1% of the molecules form H+ ions
What are the similarities in how strong and weak acids react
- When they react with magnesium they both produce hydrogen gas
- When they react with calcium carbonate they both produce carbon dioxide gas
- In both these situations they produce the same volume of gas but the rate of reaction is faster for the strong acid
What determines concentration of acids and alkalis
The amount and proportion of water present
What volume of water do dilute acids have
A high one
Why do some metals react with acids?
Because of their position on the reactivity series
Recite the reactivity series (highest to lowest)
- Potassium
- Sodium
- Calcium
- Magnesium
- Zinc
- Iron
- Tin
- Lead
- Copper
- Silver
- Gold
How do metals at the top of the reactivity series react with acids?
Vigorously and exothermically even with dilute acids
How do metals at the bottom of the reactivity series react with acids?
Not at all
What is the general equation for metals reacting with acids?
Metal + acid = metal salt + hydrogen
What kind of salts do hydrochloric acid and metals create?
Chlorides