science exam
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explain fully the TWO main methods we can use to measure the rate of a reaction.
• how quickly the reactants are used up or rate of disappearance of the product • how quickly the product are formed or the rate of appearance of the products
Rate of reaction = - - - - - - - - - - - - OR - - - - - - - - - - - - - -
amount of reactants used OR amount of product produced over time
What are some of the common ways we can measure the rate of reaction experimentally?
• precipitation • change in mass • volume of gas given off
definition of the collision theory
• in a chemical reaction there is a collision involve between the reactant particles. • theory states that the molecules must collide with sufficient energy (AE) and with suitable orientation to disrupt the bonds.
concentration applied to collision theory
• if solution is more concentrated, there is greater density of reactant particles meaning there more collisions • bc at the same proportion there is greater rate of collision • greater rate of successful collisions
subdivision applied to collision theory
• by increasing surface area, we are exposing more of the reactant • more reactant particles are available for collision • higher successful collision rate • faster reaction time
temperature applied to collision theory
1- reactant particles are moving faster meaning rate of collision increases - increase of successful collision and faster reaction time 2- increasing temp effect molecular energies of reactants - reactant have sufficient kinetic energy to supply AE needed for reaction - successful collision and faster rate of reaction
catalyst
substance that speeds up a chemical reaction but is not used up in the reaction
catalysts applied to the collision theory
• provides alternative pathway for the reaction than the one available with the reactant alone • lower AE meaning less collision energy is required
Outline the difference between a scalar measurement and a vector measurement.
scalar - quantities measured with numbers and units vector - quantities with magnitude and direction
Give two examples of a scalar quantity and two examples of a vector quantity.
scalar - speed, distance, time vector - velocity, acceleration, displacement
distance defintion
is the total amount length of a path travelled
displacement definition
is the length of a straight lined path from the beginning to end with a direction
velocity definition, classify them as scalar or vector quantities
• is the rate of change of displacement • vector • V = s/t
acceleration definition, classify them as scalar or vector quantities
• is the rate of change of velocity • vector • A = change in V/t
speed definition, classify them as scalar or vector quantities
• is the rate of change of distance • scalar • V = s/t
Describe DNA
• 2 stands of repeating units call nucleotides • responsible for passing genetic information from cell to cell • codes for protein production
describe chromosomes
• longs strands of genetic information located at the nuclei of the cell • 46 stands of DNA > 46 chromosomes
describe genes
• sequence of nucleotides found in DNA that is codes for the production of protein
DNA structure
• nucleotides twisted into a double helix - phosphate > sugar > base
what is a codon and what does it do
group of 3 bases on mRNA that codes for amino acid
what are proteins made up of
information contained in the mRNA molecule is translated into the amino acids, which are the building blocks of proteins.
Describe THREE differences between DNA and RNA
• no thymine, has uracil instead • RNA is single stranded • ribose sugars instead of deoxyribose sugars
Name the TWO processes involved in protein synthesis and where in the cell each occurs
• transcription happens in the nucleus of a cell - translation happens on a ribosome in the cytoplasm