Hello, can you help me with how to work out the following questions please? I'll show the method I used to work them out but I am not sure whether it is right or not:
25cm3 of 1.0 mol dm-3 HCl = 0.025*1=0.025 50cm3 of 0.5 mol dm-3 HCl = 0.05*0.5=0.025 250cm3 of 0.25 mol dm-3 HCl = 0.25*0.25=0.0625 500cm3 of 0.01 mol dm-3 HCl = 0.5*0.01=0.005 25cm3 of 1.0 mol dm-3 NaOH = 0.025*1=0.025
How would you calculate the mass of material in given volume of solution? e.g. 25cm3 of 1 mol dm-3 HCl and 50cm3 of 0.5 mol dm-3 NaCl?
Also, how would you work out the concentration in m,oles of dm-3? e.g. 3.65g of HCl in 1000cm3 of solution; 3.65g of HCl in 100cm3 of solution; 6.62g of Pb(NO3)2 in 250cm3 of solution; 1.00g of NaOH in 250cm3 of solution?
Hello, can you help me with how to work out the following questions please? I'll show the method I used to work them out but I am not sure whether it is right or not:
25cm3 of 1.0 mol dm-3 HCl = 0.025*1=0.025 50cm3 of 0.5 mol dm-3 HCl = 0.05*0.5=0.025 250cm3 of 0.25 mol dm-3 HCl = 0.25*0.25=0.0625 500cm3 of 0.01 mol dm-3 HCl = 0.5*0.01=0.005 25cm3 of 1.0 mol dm-3 NaOH = 0.025*1=0.025
Am I working them out correctly?
Thanks
Yeah, all of those are correct.
3.65 g of HCl in 1000 cm^3 of solution. What is the concentration in mol dm^3?
Also, how do I calculate the mass of material in the given volume of solution? I found the following equations:
molarity = concentration in grams per 1000cm3/Mr of the material dissolved number of moles of material in a given volume = (molarity x volume(cm3))/1000 mass of material in a given volume of solution = (molarity x volume(cm3) x Mr)/1000
But they are just confusing me further
I tried working out a question, I'll show you my working and can you tell where I am going wrong please.
25cm3 of 1mole dm-3 HCL
So I worked out the molarity first...
25cm3 x 4 = 1000cm3 1000cm3 / 36.5 = 27.4
Then I put this in the formula: (molarity x volume x Mr)/1000
(27.4 x 25 x 36.5)/1000 = 25
Can you PLEASE tell me how to do it, I am getting so frustrated because I can't do it, I feel like giving up *sigh*
How would I do 3.65g of HCl in 100cm3 of solution then? I'm stuck on converting the units..
Concentration = Moles / Volume
Moles = 3.65/36.5 = 0.1 (36.5 being the Mr of HCl)
Volume = 100 cm^3 = 0.1 dm^3 (as you divide by 1000 to get from cm^3 to dm^3)
Concentration = 0.1 / 0.1 = 1 mol dm^3
Also, how do I calculate the mass of material in the given volume of solution? I found the following equations:
molarity = concentration in grams per 1000cm3/Mr of the material dissolved number of moles of material in a given volume = (molarity x volume(cm3))/1000 mass of material in a given volume of solution = (molarity x volume(cm3) x Mr)/1000
But they are just confusing me further
I tried working out a question, I'll show you my working and can you tell where I am going wrong please.
25cm3 of 1mole dm-3 HCL
So I worked out the molarity first...
25cm3 x 4 = 1000cm3 1000cm3 / 36.5 = 27.4
Then I put this in the formula: (molarity x volume x Mr)/1000
(27.4 x 25 x 36.5)/1000 = 25
Can you PLEASE tell me how to do it, I am getting so frustrated because I can't do it, I feel like giving up *sigh*
OK, so the mass of a solute within a given volume is its density. In terms of equation this is Density = Mass / Volume.
You have the mass of HCl as 36.5 (molar mass). You have the volume in dm^3 of your solution as 25/1000 = 0.025 dm^3.
You merely divide the two sums to get the density. In this case 36.5/0.025 = 1460 g/dm^3 (1.46 g/cm^3).
Who in this five year old thread were you asking and expecting an answer from?
The only person I see dividing anything by 1 was Tullia, who was working out the concentration of something in 1000 cm3 = 1 dm3, and since conc = n / v (in dm3) it made sense to divide by 1, rather than dividing by 1000/1000.