Hess Law Flashcards
What is enthalpy of formation
Enthalpy change when one mole of a compound is formed it’s conscientious elements in standard states and condition and pressures
What is standard enthalpy of combustion
Wnthalpy change when one mole of compound is burnt completely oxygen all reactant and products in their standard states
What is Hess law
The enthalpy change is the same regardless of the path for reactants to products
What in bond enthalpy
Enthalpy change to break one mole of gaseous covalent bond into one mole of gaseous atoms
What is mean bond enthalpy
Avg energy to break one mole of covalent gaseous bond into gaseous atom across a range of different compounds
How to measure enthalpy change of heating water
Heat a known mass of water and then multiply by the temp change and specific heat capacity
How to use a calorimeter
Allow water to reach room temp and measure temp of water for three minutes at 4 minutes add the solute and mix throughly then add a lid and measure the temp of water from 5 minutes to 15 minutes and extrapolate to 4 th minute and measure the temp change
Why may not colorimeter give accurate reading
Heating apparatus
Energy loss to the surroundings
Incomplete combustion
How to decrease inaccuracy in colorimeter
Use a lid
Use polystyrene cup
Use a copper chimney
Reduce distance between the flame
