A) 7.5 % m / V
7.5 g -------- 100 mL ( solution )
mass g ------ 45.0 mL
mass g = 45.0 x 7.5 / 100
mass g = 337.5 / 100 => 3.375 g
1 mole KCl -------------- 74.55 g
moles KCl ---------------- 3.375 g
moles KCl = 3.375 x 1 / 74.55 => 0.0452 moles of KCl
______________________________________________
b) 9.5 % ( m / V ) :
9.5 g -------- 100 mL ( solution )
mass g ------ 400.0 mL
mass g = 400.0 x 9.5 / 100
mass g = 3800 / 100 => 38 g
1 mole acetic acid -------------- 60.05 g
moles acetid acid ---------------- 38 g
moles acetid acid = 38 x 1 / 60.05 => 0.6328 moles of acetid acid<span>
</span>______________________________________________________
hope this helps!
The time needed for a substance becomes half of it mass is called half-time, after. In this case, the half time is 100 minutes. Then to know how much substance remain after 200 minutes the equation would be:
Substance remains= 1/2^(time/half-time) x substance initial mass
Substance remains = 1/2^(200 minutes/100minutes) x 1 times= 1/4 times
The best and most correct answer among the choices provided by the question is the fourth choice or letter D.
<span>A2+ would represent the ion of an element from Group 2A</span>
I hope my answers has come to your help. God bless and have a nice day ahead!
D is the answer. It is the avagadro's constant
