Ionic Bonding, Alkali and Salts Flashcards
How can we classify substances as strong or weak acid and strong or weak alkalis?
pH Scale
What are the four 4 different types of indicators?
Litmus
Methyl Orange
Phenolphathlein
Universal Indicator
What Colour does Litmus turn when acid and alkaline?
Acid: Red
Alkali: Blue
What Colour does Methyl Orange turn when acid or alkali?
Acid: Red
Alkali:Yellow
What Colour does Phenolphthalein turn when acidic or alkaline?
Acidic: Colourless
Alkali: Pink
What is Neutralisation? What is the equation shown for this?
When acids and alkalis react forming a salt with a pH of 7
H+ (aq) + OH- (aq) —> H2O (l)
How does Neutralisation work?
Acid donates protons which are then accepted by the base.
Acid + Metal Oxide
Salt + Water
Acid + Metal Hydroxide
Salt + Water
Acid + Ammonnia
Ammonia Salt
Acid + Metal Carbonate
Salt + Water + Hydrogen
How to perform Titrations?
Using a pippette and pippette filter, add some alklali or acid (25 cm3) to a conical flask, along with two or three drops of indicator (phenophalein).
Fill a burette with the acid. Make sure you read below eye level to avoid parallax error and avoid spillage on your eyes
Using a burette, add the acid to the alkali a bit at a time to get more precise times at the end point. Also give conical flask a bit of a swirl to ensure it fuly mixes. Go slower to achieve accurate end point
The indicator changes colour when all the alkalis has been neutralised.
Record the volume of acid used to neutralise the alkali. It’s best to repeat this process a few times, making sure you get concordant results for improved reliabillity
How to work out the concentration using results from Titrations?
Work out how many moles from the substance you have
Write out the equation and find the molecular ratio to find the moles of the unkown substance
Work out concentration of unkown stuff
Why is it better to use indicators such as methyl orange, phenolpthalein etc: for titrations instead of universal indicators?
Universal Indicators are more gradual in colour change as it is more specific in pH. Therefore we cant find an accurate end point
Are all common salts of Na, K and Ammonium Soluble or insoluble?
Soluble