Quick question on Ratios and Proportions

betterfuture

2+ Year Member
If something is like:

A = 3B

This means that A is bigger than B, right? As in A is 3 times the mass of B.

Whereas if they asked for a ratio, how would that be different?
Example:
If they asked for the ratio of the weight of object A to B,

Fnet(A) = m(A)*g
Fnet(B) 3m(B)*g

Fnet(A) = 1
Fnet(B) 3

Ratio = 0.33 or 1/3

The two examples are saying the same thing or different things? It's been a long time since college algebra

I tried to write it out as a fraction but it didn't quite work out lol

The above is meant to say 1/3

aldol16

2+ Year Member
The ratio of masses of A to B is the mass of A (= 3B) to the mass of B (= B), which is 3B:1B. As a fraction, it's 3/1, or 3. That's as you would expect - A is 3 times as massive as B.

OP
B

betterfuture

2+ Year Member
So what I wrote - 1/3 - is wrong?

aldol16

2+ Year Member
So what I wrote - 1/3 - is wrong?
Yeah - you're saying that A is three times B's weight above, so the ratio of A's weight to B's weight could not be 1/3 because that would imply that A is lighter than B by a factor of 3. It is not correct for the reasons outlined in my post above.

OP
B

betterfuture

2+ Year Member
I see. Thanks.

Another quick question. If for a reaction they ask you to find the ratio of ADP/ATP concentration and they provided in the question that Pi = 1.0M

ATP + H2O ---> ADP + Pi

Wouldn't the ATP/ADP ratio be 1:1 since the equation is balanced and 1 mole of ATP gives 1 mole of ADP. It also stated Pi = 1.0M so that is why I asked thought that ADP and ATP concentrations would also be 1.0 M

But then I thought about it and it didn't make sense. The delta Go is (-) meaning equilibrium favors the forward reaction so there would be more products than reactants. But I am trying to understand why the ADP/ATP would not be 1:1. Is my reasoning wrong?

aldol16

2+ Year Member
We need more context than that. Are they saying that the [Pi] at equilibrium is 1.0 M? Or at the beginning of the reaction? You might have to do an ICE table for that. But in the ICE table, you would be correct in assuming that ATP is consumed at the same rate that ADP is formed in this particular reaction.