Astudent takes a measured volume of 3.00 m hcl to prepare a 50.0 ml sample of 1.80 m hcl. what volume of 3.00 m hci
did the student use to make the sample?
use mv - mv
sos
3.70 ml
16.7 ml
300 ml
83.3 ml
m
andum
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To solve the question you use the following formula:

concentration (1) × volume (1) = concentration (1) × volume (1)

3 M ×  volume (1)  = 1.8 M × 50 mL

volume (1)  = (1.8 M × 50 mL) / 3 M = 30 mL

30.0 ml

Explanation:

1.8 M means 1.8 moles of HCl in 1 liter (or 1000 ml) of solution.

50 ml of solution has:

1.8 moles/(x moles) = 1000 ml/(50 ml)

x = 1.8 moles/(1000 ml) * 50 ml = 0.09 moles  

3 M means 3 moles of HCl in 1 liter of solution.

0.09 moles are found in:

3 moles/(0.09 moles) = 1000 ml/(x ml)

x = 0.09 moles * 1000 ml/(3 moles) = 30 ml

Then, you have to take a sample of 30 ml of a solution 3 M and add 20 ml of the solvent (probably water) to make 50 ml of solution 1.8 M of HCl.

number of molecules / avogadro's number * molecule molecular = mass

explanation:

we define a gram-molecular weight as the mass of one mole of any element or compound. a mole contains avogadro's number of units (molecules) –  

6.022

x

10

23

. so, dividing the number of molecules by avogadro's number gives us the number of moles. multiplying that by the molecular weight gives us the mass. from the periodic table we find the gram-molecular weight of u to be238 and of f to be19. so,  

u

f

6

will have a gram-molecular weight of 352g.