Help with biology question please

Lactulose can also be used to treat people who have too high a concentration of
hydrogen ions (H+
) in their blood.
The normal range for blood H+ concentration is 3.55 × 10−8 to 4.47 × 10−8 mol dm−3

A patient was found to have a blood H+ concentration of 2.82 × 10−7 mol dm−3

Calculate the minimum percentage decrease required to bring the patient’s blood H+
concentration into the normal range.

Reply 1

macpatgh-Sheldon

The normal range for blood H+ concentration is 3.55 × 10−8 to 4.47 × 10−8 mol dm−3

A patient was found to have a blood H+ concentration of 2.82 × 10−7 mol dm−3

OK you need the %age reduction from 2.82 X 10-7 to 4.47 X 10-8 (this latter one is the higher of the normal range so will give the minimum value needed).

First, make the exponent the same in both:

So we need %age reduction from 28.2 X 10-8 to 4.47 X 10-8

You can now ignore the exponents:-
SO: Reduction needed = (28.2 - 4.47)/28.2 X 100
……………......…………= 84.1%

This sounds like a lot but remember pH = log[H+] so the pH change will still be very small.

M

Reply 2

macpatgh-Sheldon

@SincPsyco

Is my answer incorrect? Sorry!
M

Reply 3

SincPsyco

Hey, sorry for not replying and cheers for helping me out. But I don't have the mark scheme to these questions so I wasnt able to find the answer. However , I got the same answer and I asked someone else aswell who happened go get that.

Reply 4

LilyRosé

Original post by SincPsyco

Could you tell me the steps and answer please of this question

Reply 5

SincPsyco

Original post by LilyRosé

Could you tell me the steps and answer please of this question

Nah can't remember any of this sorry

Reply 6

macpatgh-Sheldon

@LilyRosé

Hi please look at my step-by-step explanation above [post no. 2] - Post no 4 suggests that my answer is correct.

Best,
M

Reply 7

MarthaMxx

Original post by macpatgh-Sheldon

The normal range for blood H+ concentration is 3.55 × 10−8 to 4.47 × 10−8 mol dm−3
A patient was found to have a blood H+ concentration of 2.82 × 10−7 mol dm−3
OK you need the %age reduction from 2.82 X 10-7 to 4.47 X 10-8 (this latter one is the higher of the normal range so will give the minimum value needed).
First, make the exponent the same in both:
So we need %age reduction from 28.2 X 10-8 to 4.47 X 10-8
You can now ignore the exponents:-
SO: Reduction needed = (28.2 - 4.47)/28.2 X 100
……………......…………= 84.1%
This sounds like a lot but remember pH = log[H+] so the pH change will still be very small.
M

Can you explain why 2.82 turned into 28.2?
and how you know that you need to divide the brackets by 28.2 to then divide it by 100?

Reply 8

macpatgh-Sheldon

Original post by MarthaMxx

Can you explain why 2.82 turned into 28.2?
and how you know that you need to divide the brackets by 28.2 to then divide it by 100?

Hi,

2.82 X 10^-7 is the same as 28.2 X 10^-8 i.e. you are multiplying 2.82 by 10 to get 28.2 SO you have to divide the exponent by 10 to keep the total value the same, yeah? This was to make the exponents the same as in the rest of the figures!

Simple maths: you are working out a percentage value so you have your starting number as numerator, the number of which you want to work out the %age as the denominator -----> this on its own will give you a fraction/decimal so to get a %age value, oc you multiply by 100, still with me?

Try to understand why you need to enter values in certain locations in calculations rather than just memorising equations: that way, you will find that it becomes a trifle :yum: