C5 Flashcards
(29 cards)
What is a mole as a number?
6x10 to the power of 23
What is the molar mass of a substance. Use water as an example
It’s relative formula mass in grams. For example water is 18 (16 for oxygen and 2 for the 2 hydrogen atoms). It’s molar mass is 18g/mol
How do you work out the empirical formulae for a compound? And what is the empirical formulae of butane? C4H10
Give it’s molecular formula in its simplest form
-C2H5
What are the sodium ions in salt needed for?
Transmitting nerve impulses and muscle contraction
Why are burettes normally filled with acid and not alkalis?
Because strong alkalis can damage glass
What can the changes of pH in an experiment be measured by?
- a pH meter
- a suitable indicator
What are single indicators?
Indicators containing a single substances. Which gives a sudden change in colour at the end point (tells only whether it is acid or alkali, not how strong)
Universal indicator is a mixed indicator. What re mixed indicators?
A indicator that contains several different indicator, and therefore changes colour over a range of pH values.
What is a titration?
A method of finding out the concentration of a acid or alkali using. Neutralisation reaction
How do you find out a pH curve (describe the method of the experiment used)
- Fill a burette full of acid
- Measure the alkali using a pipette and fill it using a pipette filler. Then pour the alkali into a conical flask
- Slowly pour the acid from the burette into the conical flask full of alkali.
How is a titration carried out?
The same as a pH curve but they use a single indicator instead of a pH meter
What is the titre?
Te volume of acid needed to exactly neutralise the alkali
Describe how to measure has using a gas syringe
The glass gas syringe is connected to the container that holds the reaction in by a tube. As the reaction takes place be tube fills up and eventually the tube is pushed out.
Describe a to carry out a upward displacement experiment.
You fill a measuring cylinder up with water and then turn it upside down in a trough full of water. The High air pressure keeps the water inside the container. As the reaction occurs the gas pushes the water out of the measuring cylinder
What is equilibrium?
A point in a reversible reaction in which a forward reaction and a backwards reaction are occurring at the same rate
What does rtp stand for?
Room temperature and pressure
One mole of any gas occupies the same volume at rtp. What is this molar volume?
24dm cubed
What are the main uses of sulphuric acid?
- phosphate fertilisers
- making chemicals
- making paper
- making polymers
- oil refining
What process is used to make sulphuric acid?
The contact process
What are the 3 raw materials needed for the contact process?
- sulfur
- air
- water
What is the 3 step process of the contact process
- Sulfur reacted with oxygen to make sulfur dioxide
- Sulfur dioxide reacted with oxygen to form sulfur trioxide
- Sulfur trioxide reacted with water to form sulfuric acid
The second stage of the contact process is a reversible reaction. What are the conditions used and why?
- 450°c : it is an exoteric reaction so a higher yield can be obtained by reducing the temperature, however the rate of reaction will be too low if the temperature is too low
- vanadium oxide : as a catalyst to speed up the reaction
- an atmospheric pressure - it provides a good yield while not being too expensive.
What acid does vinegar contain?
Ethanoic acid
What is the concentration of a acid on terms of moles?
The measure of moles of acid in 1dmcubed
