-
Looking for HSC notes and resources? Check out our Notes & Resources page
heat loss related to validity? (1 Viewer)
- Thread starter RG11
- Start date
RealiseNothing
what is that?It is Cowpea
Yes it is related to validity.
strawberrye
Premium Member
Validity is basically asking questions such as is variables controlled, is there only one independent and dependent variable and is the experimental method basically testing what it proves to test. In my opinion, changing the apparatus used does not improve its validity, but rather is related to improving the accuracy of the experiment-i.e. accuracy of the heat of combustion value obtained due to reduced heat loss. Improving validity you must consider controlling more variables such as wind flow-which can reduce take away heat radiated, temperature, apparatus used-hence why a bomb calorimeter improves validity because it specifically controls the conditions-provides an enclosed environment where variables are control, however a change of equipment from glass to insulator does not increase the number of controlled variables
A second consideration is whether your experimental aim was to compare the heat of combustions or just to determine the heat of combustions of each respective fuel, there is a slight but significant difference, because if your aim was compare-even if say, use of glass conical flask absorbs a lot of heat, but you have keep this a controlled variable, hence the heat loss will be the same, and so you can still make a valid qualitative comparison-i.e. the longer the carbon chain, the higher molecular weight alkanols have higher heat of combustions, but if your aim was to determine the heat of combustion-then you could essentially argue the crude experiment with the limited equipment in high school is invalid to determine accurate values-, you don't necessary need to have accurate heat of combustion(precise values) to make a valid qualitative comparison(in the first aim), but you will need it to make a quantitative one(as in the second aim). Hope this helps
A second consideration is whether your experimental aim was to compare the heat of combustions or just to determine the heat of combustions of each respective fuel, there is a slight but significant difference, because if your aim was compare-even if say, use of glass conical flask absorbs a lot of heat, but you have keep this a controlled variable, hence the heat loss will be the same, and so you can still make a valid qualitative comparison-i.e. the longer the carbon chain, the higher molecular weight alkanols have higher heat of combustions, but if your aim was to determine the heat of combustion-then you could essentially argue the crude experiment with the limited equipment in high school is invalid to determine accurate values-, you don't necessary need to have accurate heat of combustion(precise values) to make a valid qualitative comparison(in the first aim), but you will need it to make a quantitative one(as in the second aim). Hope this helps
Last edited: