Is an exothermic reaction, is heat given out to the surroundings or taken in heat to the surroundings?
given out
taken in
What symbol is used to show an endothermic reaction?
+
-
Do reactants have more or less chemical energy than products in an exothermic reaction?
more
less
Enthalpy change is the heat change at a constant temperature
in enthalpy changes why are standards used?
so it doesnt affect the amount of energy of the reation taken which can affect the temp
so it doesnt affect the amount of energy of the reation lost which can affect the temp
the standard enthaply change measured depends on the reaction not on the conditions
so it doesnt affect the amount of energy of the reation created which can affect the temp
What are calorimeters designed for?
to contain reactions where all the heat produced can be exchanged with the surroundings in a measurable and accurate way
to contain reactions where all the energy produced can be lost to the surroundings in a measurable and accurate way
to start reactions, providing energy which can be exchanged with the surroundings in a measurable and accurate way
What is the equation for heat produced?
Heat produced= mass x specific heat capacity of water x temp rise
Heat produced= mass x specific heat capacity of water /temp rise
Heat produced= mass / specific heat capacity of water x temp rise
How do you convert J to KJ?
/ 1000
x 1000
/ 10000
what are errors in calorimetry?
heat loss to the surroundings, by the apparatus, to the solid reactant
the concentration/ volume of the measurement
incomplete reaction
impure reactants
timings
inaccurate stirring
How do you work out percentage error?
(difference between my value and true value/ true value) x 100
(difference between my value and true value/ true value) x 1000
( true value/ difference between my value and true value) x 100
How do you convert q to ^_H?
^_= q / no. moles
^_= no. moles / q
^_= q x no.moles
What is the definition of standard enthalpy change?
when 1 mole of compound is formed from its constituent elements under standard conditions with all substances in their standard states
normal states, stable under standard conditions
heat change at a constant pressure
sodium hydroxide reacts with HCL and the container becomes really quite warm- what kind of reaction is this?
endothermic
exothermic
What is another name for the conservation of energy?
Hess' Law
Boyle's Law
Heis' Law
what kind of working out would you have to use to work out ^_H implying Hess' law
enthalpy cycles
mechanisms
equations
In bond enthalpies bonds broken is an exothermic reaction
