Three problems on my study guide that I just can't seem to figure out! Please answer with full explanation and reasoning.
1) 73.7 mL of stock ethanol was added to 26.3 mL of distilled H20 to generate a 70% ethanol solution. What was the concentration of the initial stock ethanol?
2) Explain and show your work on how you would make 50 ml of a 3M stock solution (M@ 58.44 g/mol), and then make a 100 mL of a 50mM solution from this stock solution
3) Make 100mL of a solution that is 5mM MgCl2, 5mM CaCl2, and 125 mM KCl from 0.5 stocks of each of these chemicals.