Chemistry Physical - A Level (OCR) (C0RRECTLY SOLVED)

What is the equation that relates rate, change in concentration and time. correct answers Rate = change in concentration ÷ time. How to find the units of the rate constant? correct answers 1. Rearrange the equation to make k the subject. 2. Substitute units into the expression of k 3. Cancel common units and show the final units on a single line. What is the definition of half life? Which order has a constant half life? correct answers Half life: is the time taken for half of a reactant to be used up. first order has a constant half life with the concentration halving every half life. How to calculate the rate constant from half-life? correct answers k = ln2 ÷ t1/2 What two factors affect the rate constant? correct answers 1. Increasing the temperature shifts the Boltzmann distribution to the right, increasing the proportion of particles that overcome the activation energy. 2. As the temperature increases, particles move faster and collide more frequently. What is the Arrhenius equation? What does it show? correct answers Arrhenius equation shows the effect that changing the temperature or the activation energy has on the rate constant. k = rate constant Ea =activation energy T = temperature in Kelvin R = gas constant A = approximately constant What are the units for rates? correct answers mol/dm3/s What is the format of the rate equation? correct answers k = the rate constant the powers after each chemical is the order with respect to that chemical. What is the difference between homogenous and heterogenous equilibria? correct answers Homogenous: contains equilibrium species that all have the same state or phase. Heterogenous: contains equilibrium species that all have different states or phases. What states are included in the Kc equation (i.e. solid, liquid e.t.c) correct answers aqueous and gases. How could you be sure that the reaction has reached equilibrium? correct answers 1. leave the reaction to occur for a longer period of time.