Answer: 0.174 g
Explanation:
First of all understand that charge on an atom like here 2+ will not vary molar mass. because ions are formed by loss or gain of electrons and electrons do not contribute to the mass of an atom or ion. so losing or gaining electron doesnt create any difference.
molar mass of Fe, i.e. mass of 1 mole of Fe is 56 g. So, mass of 1 mole of Fe2+ will also be 56 g.
given is 0.003109 moles of Fe2+,
Use maths,
1 mole of Fe2+ weighs 56 g
So, 0.003109 moles will weigh = (56 g / 1 mol ) x 0.003109 = 0.174 g.
Answer:
P=19.32g/cm³
Explanation:
m=9.66g
v=0.5cm³
P=mass/volume (density formula)
=9.66/0.5
=19.32g/cm³
Grinding as it’s a physical not chemical change :)
<u>Answer: </u>
A sample initially contained 150 mg of radon-222. After 11.4 days only 18.75mg of the radon-222 in the sample remained where 3 half-lives have passed
<u>Explanation:</u>
Given, the initial value of the sample, 
= 150mg
Final value of the sample or the quantity left, A = 18.75mg
Time = 11.4 days
The amount left after first half life will be ½.
The number of half-life is calculated by the formula
where N is the no. of half life
Substituting the values,
On equating, we get, N = 3
Therefore, 3 half-lives have passed.
