Unit 1 flashcards
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Unlock answers| What equation do you use to work out the rate of a reaction if it has a distinct end? |
Rate = 1/time |
| What two things are needed for a reaction to take place? |
-energy above the activation energy -collision of particles at the correct angle or orientation |
| What is Activation Energy? |
the minimum amount of energy required for a reaction |
| What is the activated complex? |
the unstable intermediate between reactants and products containing partial bonds |
| How do you calculate the enthalpy change of a reaction? |
HP- HR (enthalpy of products - enthalpy of reactants) |
| What do catalysts do? |
Catalysts lower the activation energy increasing the number of particles able to react |
| How do Heterogeneous catalysts work? |
They work by adsorbing reactants onto active sites which weakens their bonds. |
| How does poisoning of catalysts occur? |
Poisoning occurs when chemicals are absorbed onto active sites stopping them working |
| How can enzymes be denatured? |
Enzymes can be denatured if the pH, temperature or alcohol content is too extreme |
Define each component /H=cm/T
|
?H is enthalpy change c is 4.18 Kj/mol m is number of kilograms (litres) of water ?T is the temperature change |
| What step comes after working out the energy change for a certain mass of compound reacting? |
work out how much 1 mole would produce |
| Why does atomic size increase going down a group? |
there is an extra energy level moving the electrons further from the nucleus thus increasing the size |
| Why does ionisation energy increase across a period? |
It increases across a period as the electrons are closer to the nucleus therefore harder to remove |
| Why does ionisation energy decrease down a group? |
It decreases down a group as the electrons are further from the nucleus and shielded from its pull by the inner electrons |
| Why is there a large jump between the first and second ionisation energies? |
There is a large jump between the first and second ionisation energies for group 1 metals as you are removing an electron from an energy level closer to the nucleus |
| Why does electronegativity increase going across a period? |
It increases across a period as the nuclear charge increases pulling the electrons closer |
| Why does electronegativity decrease down a group? |
It decreases down a group as the pull of the nucleus is being shielded by the inner electrons |
| What do atoms with equal electronegativities form? |
Pure covalent bonds |
| What do atoms with different electronegativities form? |
POLAR covalent bonds |
| What are the symbols for the atoms with the biggest and lowest electronegativities? |
The atoms with the biggest electronegativities have a ?-charge and those with the lowest value have a ?+ charge. |
| Describe metallic bonding |
Metallic bonds have positive cores surrounded by delocalised electrons enabling the metals to conduct. |
| Where is metallic bonding found and is it strong? |
This force of attraction is very strong and exists in metal elements. |
| Describe Ionic bonding |
Ionic bonds are an electrostatic force of attraction between oppositely charged ions. |
| Describe ionic bonding's melting points ; structure |
They have high melting points and have a crystal lattice structure that must be broken before the ions are free to move and conduct electricity. |
| Are ionic compounds soluble? |
Ionic compounds are soluble in polar solvents like water |
| Describe the strength of covalent bonds |
Covalent bonds are very strong and difficult to break |
| Describe covalent Network bonding |
Covalent network substances have massive structures with millions of bonds which have to be broken to change their state |
| What are covalent molecular's at room temp and what is broken to change their state? |
•Covalent molecular substances are usually liquid or gas at room temperature.
•It is weak intermolecular forces that are broken when their state is changed |
| How are dipole-dipole attractions caused? |
Dipole –Dipole attractions are caused by molecules that have a permanent dipole
They are stronger than Van der Waals. |
| Describe Van Der Waals Strength. |
They are the weakest intermolecular force |
| What will one mole of a substance contain? |
6.02x1023 formula units |
| What will one mole of a monatomic element contain? |
6.02x1023 atoms |
| What will one mole of a diatomic and covalent molecular substance contain? |
6.02x1023 molecules
|
| What will one mole of Ionic compounds contain? |
6.02x1023 formula units |
| What happens to the molar volume of all gases at constant temperature and pressure? |
Stays the same |
| How do we work out volume of gases from a balances equation? |
We can use simple ratios to work out the volumes of gases from a balanced equation |
