Answer:
1) 90.0 mL
2) 11.25 M
3) 0.477 M
4) 144 mL
Explanation:
The main formula that will be used for all these calculations is:
C₁V₁ = C₂V₂
C stands for concentration and V stands for volume and the subscripts 1 and 2 indicate an initial concentration or volume and a final concentration or volume.
For each problem, it's best to start by figuring out what you have and what you need to find. Figure out if you're looking for an initial value or a final value.
1) We need to find the initial volume. So, take what values you have and plug them in and then solve for whatever variable:
5.00 M · V₁ = 500.0mL · 0.900 M - divide by 5.00
C₁ = 90.0 mL
2) This time we're finding the initial concentration:
20.0mL · C₁ = 150.0mL · 1.50 M - divide by 20.0mL
C₂ = 11.25 M
3) Now we're finding the final concentration:
12.00mL · 3.50 M = 88.0mL · C₂ - divide by 88.0mL
C₂ = 0.477 M
4) Finally, we're looking for the final volume:
9.0mL · 8.0 M = 0.50 M · V₂ - divide by 0.50 M
V₂ = 144mL
Answer is Mr and S as MgS ..
We must to know:
Cm = molarity = niu / Vs, when the niu = no. of moles and Vs = Volume of solution
the no. niu = mass / molecular mass of substance
molecular mass of C8H8 = 12x8+8x1 = 104 g/mol
=> niu = 1,5 / 104 = 0,0144 moles C8H8
=> Cm = 0,0144/0,225 = 0,06 mol/L
Cmm = molality = niu (C8H8) / mass of solvent (kg)
=> p = mass / V => mass (solvent) = p x V
=> 225 x 1,02 = 229,5 g solvent = 0,2295 kg solvent
=> Cmm = 0,0144 / 0,229,5 = 0,063
The mass of nucleons (and thus of the nucleus) is roughly 1000 times greater than that of electrons.
