Further analysis and quantitative chemistry Flashcards
What are moles
It’s a very big number
When you get that number of atoms it weighs the same number of grams as the atomic mass
What can concentration be measured in
Moles per dm^3
1 dm^3 = 1 litre = 1000cm^3
What is 56 grams of “stuff” dissolved in 1 dm^3 of solution?
56 grams per dm^3
What happens to the concentration when you dissolve more solute?
The more solute you dissolve in a given volume the more crowded the solute molecules and the more concentrated the solution. What
What can titrations be used for?
Titrations allow you to find out exactly how much acid is needed to neutralise a quantity of alkali (or vice versa)
Explain how you would do a titration?
Put some alkali into a flask along with some indicator,
Add the acid a drop at a time using the burette,
Swirl the flask,
When the indicator changes colour, all the alkali has been neutralised,
Record the amount of acid used to neutralise the alkali and repeat the process
What is the formula for finding the concentration in moles per dm^3
n = c * V
n = number of moles, c = concentration in mol/dm^3 V = volume in dm^3
(Triangle has n at top)
NANS CLIMB VOLCANOES
What is the formula for concentration in grams per dm^3
m = n * M_r
m= mass in grams n= number of moles M_r = relative formula mass
(Triangle with m at top)
marria needs Maddy Riaz
How can you reduce heat lost when measuring energy transfer
Adding a lid
Putting the cup into a beaker of cotton wool
What is an exothermic reaction?
An exothermic reaction is one which gives out energy to the surroundings usually in the form of heat and usually shown by a rise in temperature.
Fuels burning
Neutralisation
What is an endothermic reaction?
An endothermic reaction is one which takes in energy from the surroundings, shown by a fall in temperature
Photosynthesis
What happens to bonds during a chemical reaction?
Old bonds are broken and new bonds are formed
Explain the energy given out and taken in, in relation to bonds
Energy must be supplied to break bonds and energy is released when bonds form
What type of process is bond breaking?
Energy must be supplied to break bonds, so bond breaking is an endothermic reaction
What process is bond formation?
Energy is released when new bonds are formed, so bond formation is an exothermic process
In an endothermic reaction is the energy required greater than the energy released?
In an endothermic reaction, the energy required to break old bonds is greater than the energy released when new bonds are formed
Describe the energy released in an exothermic reaction
In an exothermic reaction, the energy released in bond formation is greater than the energy used in breaking old bonds
What is calorimetry?
Fuel energy is calculated using calorimetry
How do you measure the amount of energy released when a girl is burnt?
You burn the fuels and use the flame to heat up some water.
What is the equation for calorimetry?
Q = mc 🔼 T
Q = energy transferred in joules m = mass of water in grams c = specific heat capacity 🔼T = temperature change in degrees Celsius
What does an exothermic energy level diagram look like?
It looks like a step down
What does an endothermic energy level diagram look like?
It’s a step up
What is the activation energy
The minimum energy needed by reacting particles to break their bonds
What does a catalyst do to the activation energy!,
A catalyst lowers the activation energy
