Hi guys, I have a family member preparing some sort of pre-exam and who is stuck on this question. Obviously, I can’t solve it this is why I am posting this. (yes, sorry for that). Can anyone help us? We would like to know how to be proceed in order to get the right answer.
PS: couldn’t post a text directly in my post 🧐
To make a 100 mL solution of 5% (= 5g/100 mL) you need 5g of glucose and 100 mL of water.
You have access to a glucose solution of 25g/100 mL (=25%). This means that there is 5g of glucose in 20 mL water.
And you add 80 mL of water to make it 100 mL in total.
Honestly, the options are bad, because the only way of getting 100ml is by using 20ml 25% glucose and adding 80ml of water.
The amount of glucose is constant when afdingen water to lower the concentration.
n1 = n2
V1*c1 = V2*c2 (molair mas equals volume* concentration)
c2 is the concentration we want to get
V2 = V1*c1/c2 = 20ml
then we add 80ml of water to get to 100ml
3 comments
Hi guys, I have a family member preparing some sort of pre-exam and who is stuck on this question. Obviously, I can’t solve it this is why I am posting this. (yes, sorry for that). Can anyone help us? We would like to know how to be proceed in order to get the right answer.
PS: couldn’t post a text directly in my post 🧐
To make a 100 mL solution of 5% (= 5g/100 mL) you need 5g of glucose and 100 mL of water.
You have access to a glucose solution of 25g/100 mL (=25%). This means that there is 5g of glucose in 20 mL water.
And you add 80 mL of water to make it 100 mL in total.
Honestly, the options are bad, because the only way of getting 100ml is by using 20ml 25% glucose and adding 80ml of water.
The amount of glucose is constant when afdingen water to lower the concentration.
n1 = n2
V1*c1 = V2*c2 (molair mas equals volume* concentration)
c2 is the concentration we want to get
V2 = V1*c1/c2 = 20ml
then we add 80ml of water to get to 100ml