a level chemistry
can someone explain/help me with this question? I just joined the subject chem and missed out on how to do this:
The solubility of a substance is a measure of how much of it will dissolve in a given solvent. At 20 °C, the solubility of calcium hydroxide (Ca(OH)2) in water is 0.0233 mol dm−3. Calculate the maximum amount, in grams, that will dissolve in 250 cm3.
The solubility of a substance is a measure of how much of it will dissolve in a given solvent. At 20 °C, the solubility of calcium hydroxide (Ca(OH)2) in water is 0.0233 mol dm−3. Calculate the maximum amount, in grams, that will dissolve in 250 cm3.
I am a fellow As Chemistry learner so I may get this wrong, but
Concentration=mass/volume so rearrange to get mass=conc x volume
Volume in dm^3 though so you got to x10^-3 (divide by 1,000) to get 250x10^-3dm^3
So substitute it in= 0.0233x 250x10^-3=5.825x 10^-3g but to 3sf as 5.83x10^-3g
I tried
Concentration=mass/volume so rearrange to get mass=conc x volume
Volume in dm^3 though so you got to x10^-3 (divide by 1,000) to get 250x10^-3dm^3
So substitute it in= 0.0233x 250x10^-3=5.825x 10^-3g but to 3sf as 5.83x10^-3g
I tried
Original post by rubyroserm
can someone explain/help me with this question? I just joined the subject chem and missed out on how to do this:
The solubility of a substance is a measure of how much of it will dissolve in a given solvent. At 20 °C, the solubility of calcium hydroxide (Ca(OH)2) in water is 0.0233 mol dm−3. Calculate the maximum amount, in grams, that will dissolve in 250 cm3.
The solubility of a substance is a measure of how much of it will dissolve in a given solvent. At 20 °C, the solubility of calcium hydroxide (Ca(OH)2) in water is 0.0233 mol dm−3. Calculate the maximum amount, in grams, that will dissolve in 250 cm3.
Concentration = number of mole/volume. You are given the concentration of 0.02333mol/dm3. You are also given the volume of your solution, 250 cm3 = 0.250 dm3. Rearranging the equation, we get the formula for the number of moles: moles = concentration x volume. Moles of Ca(OH)2 = 0.0233 mol/dm3 x 0.250 dm3 = 0.00583 moles. Now all you need to do is convert moles into grams. Mr of Ca(OH)2 = 74 g/mol. Mass = number of moles x Mr = 0.00583 moles x 74 g/mol = 0.431 g. Hope this helps.
Original post by Quack#1
I am a fellow As Chemistry learner so I may get this wrong, but
Concentration=mass/volume so rearrange to get mass=conc x volume
Volume in dm^3 though so you got to x10^-3 (divide by 1,000) to get 250x10^-3dm^3
So substitute it in= 0.0233x 250x10^-3=5.825x 10^-3g but to 3sf as 5.83x10^-3g
I tried
Concentration=mass/volume so rearrange to get mass=conc x volume
Volume in dm^3 though so you got to x10^-3 (divide by 1,000) to get 250x10^-3dm^3
So substitute it in= 0.0233x 250x10^-3=5.825x 10^-3g but to 3sf as 5.83x10^-3g
I tried
Your definition of the concentration is incorrect. Concentration = number of moles/volume. Not mass! See my answer to the topic starter for the explanation.
Original post by Quack#1
I keep forgetting it's c=n/v not c=m/v
Honestly with all those equations just do make it so n is the subject. e.g
n=cv
n=v/24
Pv=nrt - this is an exception.
n=mass/mr
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