Acids Flashcards
What measurement do we use to see how acidic or alkaline a substance is?
pH scale
What is the pH of an acid?
pH 1-6
What is the pH of an alkali?
pH 8-14
What name is given to a substance that changes colour depending on how acid or alkaline a substance is?
Indicator
Name 3 indicators
Any 3: universal indicator, litmus, methyl orange, phenolphthalein
How do you describe a substance with pH7?
Neutral
Name three acids
Any 3: Hydrochloric, nitric, sulphuric, ethanoic
Name an alkali
Sodium hydroxide
Name two neutral substances
Water, salty water
Why are concentrated acids and alkalis hazardous?
They are corrosive
Why are dilute acids and alkalis hazardous?
They are irritants
What safety precautions should you make when using acids and alkalis
Wear goggles, wear gloves
When acids dissolve in water, what ions do they release?
Hydrogen ions, H+
When alkalis dissolve in water, what ions do they release?
Hydroxide ions, OH-
What is a base?
A substance that reacts with an acid in a neutralisation reaction
What is an alkali?
A soluble base, e.g. sodium hydroxide
What happens to the H+ and OH- ions from the acid and base during neutralisation?
They react together to form water:
H+ + OH- –> H2O
What factor does an acid need to be diluted by to increase the pH by 1?
10
What factor does an alkali need to be diluted by to decrease the pH by 1?
10
What is the difference between a strong acid and a weak acid?
Strong acids fully dissociate, weak acids slightly dissociate
What is the difference between a concentrated acid and a dilute acid?
Concentrated acids have lots of acid particles in a given volume. Dilute acids have fewer particles in a given volume.
What are the units for concentration?
mol/dm3 (moles per cubic decimetre)
Two acids have H+ concentrations of 1mol/dm3 and 0.001mol/dm3. What is the difference in pH?
3
Two alkalis have OH- concentrations of 0.1 and 0.00001mol/dm3. What is the difference in pH?
4
