C3.4 Acids, ions, and metals Flashcards Preview

Chemistry > C3.4 Acids, ions, and metals > Flashcards

Flashcards in C3.4 Acids, ions, and metals Deck (14):

What can a flame test be used for?

To detect the presence of a metal ion in a compound


How do you complete a flame test?

Dip a clean loop in the sample solution
Hold the flame test in the bunsen burner flame
Observe the colour of the flame


How do you test for positive ions ( cations )

eg SODIUM bromide

-Dissolve a small amount in water
-Add sodium hydroxide solution
- Identify the colour of the precipitate formed

If there is a WHITE precipitate, add MORE sodium hydroxide, If the precipitate does not dissolve, DO A FLAME TEST


What colour precipitate does iron II form



What cation forms a red/brown precipitate?

Iron III


How can you identify copper?

Blue precipitate


What colour flames do Lithium, Magnesium, and Sodium produce?

Lithium = Red
Magnesium = No colour
Sodium = Yellow


Which cations would lilac or brick red flames indicate?

Lilac = potassium
Brick red = calcium


How do you test for negative ions (anions)?

-Dissolve in water
- Add Hydrochloric acid

If A gas is given off = CARBONATE
If no gas is given off ....

-Add hydrochloric acid + Barium chloride
If a white precipitate is formed = SULPHATE
-Add nitric acid and silver nitrate to fresh solution
identify the colour precipitate formed


What ion is present when a white precipitate is formed?



How do you identify a BROMIDE ion

Forms a CREAM precipitate with nitric acid and silver nitrate


What ion is present when a YELLOW precipitate is formed?



How are titrations used to identify the acidity of a solution?

Titrations can be used to determine the volume of acid and alkali needed to react together to produce a neutral solution


25 cm3 of dilute hydrochloric acid is neutralised by 20 cm3 of 0.5 mol/dm3 sodium hydroxide. What is the concentration of the hydrochloric acid?

-Convert volumes to dm3
-Determine the number of moles of sodium hydroxide
(moles of NaOH = concentration × volume)
-Work out the number of moles of acid using the balanced equation
- Calculate the concentration of the acid
(concentration of HCl = number of moles ÷ volume)

Ans = 0.4mol/dm3