Make a quick chart with each element represented, and count them up. HINT - leave the polyatomic anions together - in this case, PO4
Left Right
1 Ca 3
2 O 1
5 H 2
1 PO4 2
Begin by balancing like finding common denominators of fractions - apply to both sides:
I started by adding a 2 in front of H3PO4 on the left, them 6 in front of H2O on the right. Last, a 3 in front of Ca (OH)2. Then, re-count using the chart format to make sure you're right.
3Ca(OH)2 + 2H3PO4 = Ca3(PO4)2 + 6H2O
Answer:0.286M
Explanation:
10.7g / 149.89g/mol×0.25L
Answer : The time required for decay is, 84 days.
Explanation :
Half-life of chromium-51 = 28 days
First we have to calculate the rate constant, we use the formula :



Now we have to calculate the time required for decay.
Expression for rate law for first order kinetics is given by:

where,
k = rate constant
t = time taken by sample = ?
a = let initial activity of the sample = 100
a - x = amount left after decay process = 12.5
Now put all the given values in above equation, we get


Therefore, the time required for decay is, 84 days.