Answer:
About 1.254 moles
Explanation:
The first step is to find the molar mass of selenium. If you take a look at a periodic table, you will find that there is a little number underneath that says something around 78.96 g/mol. Dividing 99 grams by this number, you get about 1.254 moles of Se. Hope this helps!
HI There!
Which of the following is NOT the same as 13.6 milliliters?- 0.0136 dkL
- 0.0136 L
- 0.136 dL
Answer:<span>0.0136 dkL</span>
At STP, 1 mol = 22.4
1 mol = 6.022 X 10^ 23
so your answer is right it is B 6.022 X 10^ 23
Hello,
I believe this is (25 g Al) * (1 mol H / 1.008 g H) = 24.8015 mol H
Hopefully that was the right approach.
I thought that if one mole of Al is
26.982 g, then the numbers of moles for H (1.008 g/mol) would be about 25 mol.
If it doesn’t make sense or if you have resources/notes to which I can refer, I’ll see what I can do!
Good luck!
You can split the process in two parts:
1) heating the liquid water from 10.1 °C to 25.0 °C , and
2) vaporization of liquid water at constant temperature of 25.0 °C.
For the first part, you use the formula ΔH = m*Cs*ΔT
ΔH = 30.1g * 4.18 j/(g°C)*(25.0°C - 10.1°C) = 1,874 J
For the second part, you use the formula ΔH = n*ΔHvap
Where n is the number of moles, which is calculated using the mass and the molar mass of the water:
n = mass / [molar mass] = 30.1 g / 18.0 g/mol = 1.67 mol
=> ΔH = 1.67 mol * 44,000 J / mol = 73,480 J
3) The enthalpy change of the process is the sum of both changes:
ΔH total = 1,874 J + 73,480 J = 75,354 J
Answer: 75,354 J
