Bio test #2 Grade 10 Flashcards
chemical equation of experiment
2h2o2 -> 2h20 + 02
What is the enzyme used in this reaction
catalase
Ingredients
potato puree
hydrogen peroxide
alkalines (naoh)
acids (hcl)
what are enzymes
biological catalysts that speed up the rate of chemical reactions without being changed or consumed
how do enzymes work
- active site is specific to only one type of reaction
- can catalyze infinite amount of reactions
what is pH
per hydrogen
measures the acidity or alkalinity of the substance
ionization
occurs when pure water separates into h+ and oh- ions
occurs because chemical bonds are not infinitely strong
what are acids
any substance that when added to an aqueous solution causes an excess of h+ ions
what is an alkaline
any substance that when added to an aqueous solution causes an excess of oh- ions
why does the active site get denatured when acids are added to the solution
because the hcl ionizes into h+ and cl-, which causes an excess of h+. The excess h+ bond with the negatively charged amino acids (in the hydrogen bonds) which break the bonds
why does the active site get denatured when akalis are added to the solution
because the NaOh ionizes into na+ and oh-, which causes an excess of oh-. The excess oh- bond with the positively charged amino acids (in the hydrogen bonds) which break the bonds
what are the products and reactants
hydrogen peroxide -> oxygen + water
research question
what is the effect of changing pH on the rate of reaction catalyzed by catalase
Hypothesis
At acidic pH (4.0 - 6.0), the rate of reaction will be slow and will increase as the pH gets closer to neutral. This is because the excess h+ will break the hydrogen bonds that give the enzyme it’s unique shape. At neutral pH (7.0), the rate of reaction will be at its highest since the h+ and oh- ions will be in balance. At alkaline pH (8.0 - 11.0), the rate of reaction will slow down once again due to the excess oh- denaturing the active site. Overall, the more acidic or alkaline the solution is, the slower the rate of reaction will be.
Independent variable
pH
dependent variable
rate of reaction (oxygen gas produced in 30s)
fixed variables
- temp h202
- temp potato puree
- volume h202
- volume potato puree
- time of each reaction
- concentration of hydrogen peroxide solution
- amount of light
- collection method
defects of experiment
- oxygen gas lost as a result of the collection method
- discrepancies between how each group collected their data
solutions to problems
- adding a hole with a secure lid to the ‘lid’ of the beaker to lose less oxygen gas
- having one person collect all data to ensure it is done in a consistent manner
how to graph
- ph on x
- rate of reaction on y
- curve of best fit starting at first and ending at last point
- title and axis titles
- use ruler
why do we do multiple trials
because there is variability in life
when there are mutliple trials, we calculate the mean
mean
add up all elements then divide by the amount
- useful as it accounts for variability and gets us closer to the true value
purpose of a graph
visual representation - allows us to draw conclusions we wouldn’t be able to otherwise
measurement uncertainty
degree to which we can measure precisely
- after the measurement, add +/- ___
- in the ___ we put to what place the form of measurement goes to
- ex. thermometer only goes to ones place, so it would be 17C +/- 1C
ruler goes to one tenths place so it would be 50.9cm +/- 0.1cm
