questions, errors and risks

explain why its impt to keep variable same

ensure only variable changes is…

Account for differences (one liquid, one solid)

solid (high temperature cooking) protein denatured

describing trends

1. As A inc/dec from X-Y, B inc/dec from V-W

2. 2nd trend

3. optimum A is C

Describe 2 ways you ensured different concentrations of H2O2 was prepared accurately

1. ensure no bubbles drawn into syring by ensuring mouth of syringe stays submerged in liquid

2. ensure each 10cm3 syringe used to dispense only 1 sol. Ensure no cross contamination btw H2O2 of diff stock concentrations

Why impt to stir sol

even distibution of A added into each test tube

different distance

inconsistent light intensity→do separately/arrange to be same distance

temperature

not constant since absorb more heat→immerse in water bath

lack repeats

compromises reliability→2 repeats and find mean ensure reliable

reuse syringe

changes concentration→use 1 syringe per sample

measuring cylinder

less precise→use 1cm3 and 10cm3 syringes

interval/range btw IV to wide/narrow

inc/dec interval/range by inc no. of data pts.

colour change observed visually

visual comparison subjected, inaccurate results→colour chart to compare

pour up to certain depth

vol not standardised/accurate→use syringe for precise

count bubbles too fast and no repeat

dilute yeast suspension/lower temp

chemical irritant

where gloves prevent contact to skin

knife cause cuts

use tile and hold specimen firmly

liquid splash when boiling

safety goggles

open flame

dont leave unattended. turn off if leaving bench