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Calculating Ratios

Teacher Notes

Calculating Ratios to Find New Quantities of Substances

Respiration
C6H12O6
+ 6O2
—› 6H2O
+ 6CO2
+ 36 ATP (670 kcal)
glucose
+ oxygen
—› water
+ carbon dioxide
+ energy

Table 1. Calculating kilogram inputs and outputs of respiration
Measures
Compounds
ATPEnergy

Glucose
A

Oxygen
B

Water
C

Carbon dioxide
D


(moles)

(kcal)>
E

moles
1
6
6
6
36
670
grams
1 x 180.16 = 180.16
6 x 32.00 = 192.00
6 x 18.02 = 108.12
6 x 44.01 = 264.06
36
670
kilograms
0.18016
0.19200
0.10812
0.26406
36
670
kg/day     
*


    C6H12O6+ 6O2—› 6H2O + 6CO2+ 36 ATP (670 kcal)
    A+ B—› C+ D+ E kcal
    X (A+ B—› C+ D+ E kcal)
    XA+ XB—› XC+ XD
    + XE kcal

What is X? X is the FACTOR by which if one quantity increases, all quantities must increase.

    X x E = New E where E is the original kcal quantity
    X = New E / E

The factor, X, is the same for all compounds and kcal.

X = New E / E = New A / A = New B / B = New C / C = New D / D

Thus, if any one new quantity is known, it can be used to find the factor that is multiplied by all the original quantities to obtain the other new quantities.

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