(46x8.0)+(47x7.8)+(48x73.4)+(49x5.5)+(50x5.3) = 4792.3
4792.3/100 = 47.923 this is the average atomic mass of Titanium
In this kind of exercises, you should use the "ideal gas" rules: PV = nRT
P should be in Pascal:
445mmHg = 59328Pa
1225mmHg = 163319Pa
V should be in cubic meter:
16L = 0.016 m3
R =
= constant
=
==> P1 * V1 = P2 * V2
V2 =
=
V2 = 0.00581 m3 = 5.81 L
In 1 mole of 
, there are 3 moles of ions, 1 mole of Ca^{2+} and 2 mole of 
.
Molar mass of is 110.98 g/mol. Calculating number of moles from given mass as follows:
Thus, number of moles of ions will be 
.
Since, 1 mole of any substance has 
units of that substance where is Avogadro's number.
Thus, 9.38 mol of ions will have 
number of ions.
Therefore, total number of ions in 347 g of is 
.
Molarity is defined as number of moles of solute in 1 L of solution.
Here, 0.1025 g of Cu is reacted with 35 mL of HNO_{3} to produced Cu^{2+} ions.
The balanced reaction will be as follows:
Cu+3HNO_{3}\rightarrow Cu(NO_{3})_{2}+NO_{2}+H_{2}O
From the above reaction, 1 mole of Cu produces 1 mole of Cu^{2+}, convert the mass of Cu into number of moles as follows:
n=\frac{m}{M}
molar mass of Cu is 63.55 g/mol thus,
n=\frac{0.1025 g}{63.55 g/mol}=0.0016 mol
Now, total molarity of solution, after addition of water is 200 mL or 0.2 L can be calculated as follows:
M=\frac{n}{V}=\frac{0.0016 mol}{0.2 L}=0.008 mol/L=0.008 M
Thus, molarity of Cu^{2+} is 0.008 M.
The correct answer would be the third option. If a solution process is exothermic, the energy required is less than the energy released. An exothermic reaction is a reaction that releases energy to the surroundings. The energy released should be more than what is absorbed in order to maintain the reaction.
