6.3- Acids have low pH, bases have high pH

Question 1

Acids

Answer 1

A group of chemical compounds with similar properties with at least one hydrogen atom and react with many metals. o Strong (laboratory) acids are dangerous as they can burn through objects. They include hydrochloric acids, sulfuric acid, and nitric acid. Weak (organic) acids are safer- we can eat or drink some of them. They include carbonic acid, acetate, citric acid, ascorbic acid. Strong acids donate their protons more easily- more acidic that weak acids. Acids act a preservation by preventing the growth of microorganisms. They have a sour taste.

Question 2

Bases

Answer 2

These are the opposite of acids and have a bitter taste and feel slippery/soapy to touch. - They can dissolve in water they are called alkalis- solutions that are formed by these soluble bases are called alkaline solutions. They are used in cleaning agents.

Question 3

Difference between two

Answer 3

• Taste, touch, or smell- not always safe
• An indicator is a substance that changes colour in the presence of an acid or base
• Scientists use litmus paper and an universal indicator
• Litmus paper is the most common indicator to test whether the substance is an acid or base
  o Turns red in acidic solutions and blue in basic solutions
• Universal indicators are a mixture of different indicators- more accurate as it indicates the strength of the acidic or basic solution that it is testing

Question 4

Concentrated and dilute acids

Answer 4

Concentrated acids have a large number of acid molecules per litre of solution. Dilute acids have a smaller number of acid molecules per litre of solution. Strength and concentration of an acid are not the same

Question 5

pH

Answer 5

pH scale describes the relative acidity or alkalinity of a solution. All acids have a pH less than 7. Depends on the strength and concentration of an acid. A strong, concentrated acid may have a pH of less than 1. A weak, dilute acid may have a pH between 6 and 7. If a solution is neutral- neither acid or base- is has a pH of 7 (e.g. water). Alkalis have a pH value greater than 7. Strong bases can form solutions with a pH up to 14