If i start with 46 ml of 1.25 m hcl and dilute it to a volume of 250 ml, what is the concentration of my final solution

Equation: M1V1 = M2V2

Where M = concentration & V = volume

Step 1: Write down what is given and what you are trying to find

Given: M1 = 1.25M, V1 = 46mL, and V2 = 250mL
Find: M2

Step 2: Plug in the values into the equation

M1V1 = M2V2
(1.25M)(46mL) = (M2)(250mL)

Step 3: Isolate the variable (Divide both sides by 250mL so M2 is by itself)

(1.25M)(46mL) / (250mL) = M2

M2 = 0.23M 

Moles = mass/molar mass the molar mass of c20 = 12.011*20 = 240.22 g per mole therefore, the number of moles is 20 g / 240.22 g per mol = 0.0833 moles.