Elements are made of only one kind of atom. The molecule is made up of two or more kinds of atoms. There is no physical change that can separate the compounds into more than one kind of substance. This makes a compound a pure substance.
Answer:

Explanation:




= 0.64 kJ/mol = 640 J/mol
R = 8.314 J/mol.K
Using Van't Hoff Equation:








Answer:
1.16atm
Explanation:
We are going to derive the mass of ether from density
mass=density *volume
Also moles=mass/molecular mass
molar mass C2H5OC2H5 =74.12 g/mole
the density of ether is 0.7134 g/ml
mass C2H5OC2H5 = 5.30 ml x 0.7134 g/ml = 3.78 g
moles C2H5OC2H5 =3.78 g x 1 mole/74.12 g = 0.0509 moles
PV = nRT where P=?; n=0.0509 moles; V=6.50L; R=0.0821 Latm/Kmol; T=35ºC +273 = 308K
P = nRT/V = 0.0509)(0.0821)(308)/6.50
P = 0.198 atm (to 3 significant figures (this is the partial pressure of diethyl ether).
TOTAL PRESSURE
P1+p2+p3
= 0.198 atm + 0.750 atm + 0.207 atm =1.1550atm
1.16atm(3 significant figures)
Number of molecules in 1 dm³ Oxygen = 2.71 x 10²²
<h3>Further explanation</h3>
Conditions at T 0 ° C and P 1 atm are stated by STP (Standard Temperature and Pressure). At STP, Vm is 22.4 liters/mol.
The mole is the number of particles contained in a substance
1 mol = 6.02.10²³
1 dm³ of oxygen = 1 L Oxygen

n=mol=0.045
No = 6.02.10²³

Im not positive but i think it is When it is a gas?