Further analysis and quantitative chemistry Flashcards
What can be used to identify metal ions?
Flame tests and precipitation of metal ions.
What is the method to do a flame test?
- Heat and then dip a piece of nichrome wire in concentrated hydrochloric acid to clean it.
- Dip the wire in the compound.
- Put it into a Bunsen flame.
- Notice a distinctive coloured flame is produced in the presence of certain ions.
In a flame test, what colour will the flame turn if barium is present?
Green.
In a flame test, what colour will the flame turn if calcium is present?
Brick red.
In a flame test, what colour will the flame turn if lithium is present?
Crimson red.
In a flame test, what colour will the flame turn if potassium is present?
Lilac.
In a flame test, what colour will the flame turn if sodium is present?
Yellow.
What do carbonates react with dilute acids to form?
Carbon dioxide gas and a salt and water.
How can carbon dioxide be tested for?
Bubbling through limewater, which will turn milky.
What is titration?
An accurate technique that can be used to find out how much of an acid is needed to neutralise an alkali.
What happens to the ions during neutralisation?
The hydrogen ions from the acid join with the hydroxide ions from the alkali to form water.
What is the word equation for neutralisation?
hydrogen ion + hydroxide ion -> water molecule.
What is the symbol equation for neutralisation?
H^+ + OH^- -> H2O
What is the method for titration?
- Wash and rinse a pipette with the alkali.
- Use the pipette to measure out a known and accurate volume of the alkali.
- Place the alkali in a clean, dry conical flask.
- Add a suitable indicator, for example phenolphthalein.
- Place the acid in a burette that has been washed and rinsed with the acid.
- Take an initial reading of the volume of acid.
- Carefully add the acid to the alkali until the indicator changes colour to show neutrality. This is called the end point.
- Take a final reading of the volume of acid in the burette.
- Calculate the volume of acid added.
How do you spell phenolphthalein?
P-H-E-N-O-L-P-H-T-H-A-L-E-I-N
2 reasons why titration method should be repeated.
- To check results.
2. To then be performed without an indicator in order to obtain the salt.
What two things can titration be used for?
- To find out how much of an acid is needed to neutralise an alkali.
- To find the concentration of an acid or alkali providing that the relative volumes of both the acid and the alkali or the concentration of the other acid or alkali is known.
How can the concentration of an acid or alkali be worked out using titration?
- Write down a balanced symbol equation.
- Determine the ratio of moles of acid to alkali.
- Calculate the number of moles in the solution of the known volume.
- Calculate the concentration of the other solution.