chemistry c6 Flashcards
what is a catalyst
a catalyst speeds up the rate of reaction by providing a alternative route with a lower activation energy it is chemically unchanged at the end of the reaction
write a balanced symbol equation for the Haber process
N2(g)+3H2 (g)⇌ 2NH3 (g)
what is activation energy
the energy required to break bonds and start the reaction
how can we measure the rate of reaction of a reaction that produces a gas
by measuring the volume of gas produced or the mass lost
how can we work out the rate of reaction from a graph of volume of gas vs time
calculating the gradient of the tangent to the curve
explain what happens to the position of the equilibrium when you decrease the temperature ( exo)
the position of the equilibrium moves in the direction of the exothermic reaction
explain how the surface area changes the rate of reaction
increasing the surface area means more frequent collisions and a higher rate of reaction
write the word equation for the haber process
nitrogen + hydrogen —–> ammonia
what is the symbol for a reversible reaction
⇌
how can we identify a catalyst in a reaction
(speeds ip…)
it speeds up the rate of reaction and doesn’t get used up
why don’t industrial synthesis every use very high pressures
too dangerous and equipment is too expensive
why dont industrial synthesis ever use very high temperatures
( energy)
requires to much energy
explain what happens to the position of a equilibrium when you add a product
( l to re)
the position of equilibrium moves to the left to remove some of these products
explain how catalysts change the rate of a reaction
(decrease activation energy)
(energy greater than…)
catalyst decrease the activation energy so there are more frequent successful collisions with energy greater than the activation energy
what is the biggest source of error when your measuring the volume of gas produced
( reaction vessle)
gas lost before the top is put on the reaction vessel
explain what happens to the position of equilibrium when you increase the temperature
the position of the equilibrium moves in the direction of the endothermic reaction
if a reaction forms a principatee how can we measure the rate
measure the time it takes for a cross placed under the reaction to disappear calculate 1/time to find the rate
explain what happens to the position of the equilibrium when you remove a product
the position of the equilibrium moves to the right to add more products
what can we use to measure the volume of gas produced
gas syringe or upside down measuring cylinder full of water
explain how concentration changes the rate of reaction
increasing the concentration means more particles in the same volume more frequent collisions and a high rate of reactions
explain what happens to the position of equilibrium when you decrease the pressure
(less pressure more moles )
the position of the equilibrium moves to the side with more moles of gas
explain how particle size changes the rate of a reaction
smaller particle size means higher surface area , more frequent collisions and a higher rate of reaction
why don’t reversible reactions in a closed system produce 100% yield
at equilibrium there is a mixture of reactants and products
explain how temperature changes the rate of reactions
( fast ,energy,energy> active energy)
increasing temperature means particles move faster and with more energy so there are more frequent successful collisions with energy greater than the activation energy
