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equation for mean rate of reaction
total quantity (g or cm³) / time taken (s)
equation for moles (solid)
mass (g) / molar mass (g/mol)
molar volume of gas
24 dm³/mol
equation for moles (gas at room temperature)
volume of gas (dm³) / 24 dm³/mol
cm³ → dm³
divide by 1000
what 4 conditions can increase the rate of reaction?
how does higher temperatures increase the rate?
increase surface area
high temperature
high concentration
high pressure
more kinetic energy is transferred which increases amount of collisions
why do smaller objects such as powders increase the rate of reaction?
have a larger surface area to volume ratio, therefore more collisions take place
collision theory
chemical reactions can only occur when particles collide with enough energy
activation energy
the minimum amount of energy that particles must have to react
catalyst
substances which increase rate of chemical reaction by providing an alternative reaction pathway with a lower activation energy
test for hydrogen
burn splint
hold splint above tube until a squeaky pop sound is made
how can the student investigate how the rate of reaction when the concentration of is changed by measuring the volume of gas produced?
use 50cm³ of 1mol/dm³ hydrochloric acid
use 3cm magnesium ribbon
set up a conical flask containing 50cm³ of 1mol/dm³ hydrochloric acid
have bung and delivery tube attached to gas syringe prepared
add a 3cm piece of magnesium ribbon
quickly fit bung on conical flask and start a stopwatch
record the measurement of gas produced every 10 seconds
repeat experiment with 2 and 3 mol/dm³ hydrochloric acid
how can the student investigate how the rate of reaction when the concentration of is changed by observing change of colour or turbidity?
use 10cm³ sodium thiosulfate solution
use 10cm³ dilute hydrochloric acid
pour 10cm³ of sodium thiosulfate solution into a conical flask
measure out 40cm³ water with a measuring cylinder and pour into conical flask
add 10cm³ dilute hydrochloric acid into conical flask and place it on a black cross and start a stopwatch
record the time it takes for the cross to disappear
repeat using other concentrations of sodium thiosulfate
