Answer: 10.2 grams
Explanation:
The balanced chemical reaction is :
According to the ideal gas equation:
P = Pressure of the gas = 740 torr = 0.97 atm (760torr=1atm)
V= Volume of the gas = 12.0 L
T= Temperature of the gas = 19°C = 292 K 
R= Gas constant = 0.0821 atmL/K mol
n= moles of gas
According to stoichiometry:
2 moles of hydrogen are generated by = 1 mole of 
Thus 0.48 moles of hydrogen are generated by =
moles of
Mass of 
Thus 10.2 grams of are needed to generate 12.0 L of hydrogen gas if the pressure of hydrogen is 740. torr at 19°C
Ca(NO3)2 -------> Ca²⁺ +2NO3⁻
M(Ca(NO3)2)= M(Ca) + M(N) + 6M(O)= 40.0 +14.0 +6*16.0 = 150 g/mol
15.0 g Ca(NO3)2 * 1mol/150 g = 0. 100 mol Ca(NO3)2
Ca(NO3)2 -------> Ca²⁺ +2NO3⁻
1 mol 2 mol
0.100 mol 0.200 mol
We have 0.2 mol NO3⁻ in 300. mL=0.300 L of solution,
so
0.200 mol NO3⁻ / 0.300 L solution ≈ 0.667 mol NO3⁻ /L solution = 0.667 M
Concentration of NO3⁻ is 0.667 M.
Answer:
A
Explanation:
The letter A is the correct answer
