All elements have a AHf, of <u>0</u>
kJ/mole at standard temperature and pressure.
<h3>What is an element?</h3>
An element can be defined as a substance which cannot be split into two or more simpler forms by an ordinary chemical process
Below are the list of the first twenty elements:
- Hydrogen
- Helium
- Lithium
- Berylium
- Boron
- Carbon
- Nitrogen
- Oxygen
- Fluorine
- Neon
- Sodium
- Magnesium
- Aluminum
- Silicon
- Phosphorus
- Sulphur
- Chlorine
- Argon
- Potassium
- Calcium
So therefore, all elements have a AHf, of <u>0</u>
kJ/mole at standard temperature and pressure.
Learn more about elements:
brainly.com/question/11829854
#SPJ1
Answer:
Mass percent N₂ = 89%
Mass percent H₂ = 11%
Explanation:
First we <u>use PV=nRT to calculate n</u>, which is the total number of moles of nitrogen and hydrogen:
- 1.03 atm * 7.45 L = n * 0.082 atm·L·mol⁻¹·K⁻¹ * 305 K
So now we know that
- MolH₂ + MolN₂ = 0.307 mol
and
- MolH₂ * 2 g/mol + MolN₂ * 28 g/mol = 3.49 g
So we have a <u>system of two equations and two unknowns</u>. We use algebra to solve it:
Express MolH₂ in terms of MolN₂:
- MolH₂ + MolN₂ = 0.307 mol
Replace that value in the second equation:
- MolH₂ * 2 g/mol + MolN₂ * 28 g/mol = 3.49
- (0.307-MolN₂) * 2 + MolN₂ * 28 = 3.49
- 0.614 - 2MolN₂ + 28molN₂ = 3.49
Now we calculate MolH₂:
- MolH₂ + MolN₂ = 0.307 mol
Finally, we convert each of those mol numbers to mass, to <u>calculate the mass percent</u>:
- N₂ ⇒ 0.111 mol * 28 g/mol = 3.108 g N₂
- H₂ ⇒ 0.196 mol * 2 g/mol = 0.392 g H₂
Mass % N₂ = 3.108/3.49 * 100% = 89.05% ≅ 89%
Mass % H₂ = 0.392/3.49 * 100% = 11.15% ≅ 11%
Answer:
179 L of CO2
Explanation:
Given the equation of the reaction;
C2H6(g) + 7/2 O2(g) -------> 2CO2(g) + 3H2O(g)
Now 1 mole of ethane yields 2 moles of CO2 from the balanced reaction equation
1 mole of a gas occupies 22.4 L volume so,
22.4 L of ethane yields 44.8 L of CO2
89.5 L of ethane yields 89.5 * 44.8/22.4 = 179 L of CO2
