To get the melting point of a solution so, we will use this formula:
ΔT = - mKf
when:
m is molality of the solution
Kf is cryoscopic constant of water = 1.86 C/m
and ΔT is the change in melting point (T2 - 0 °C)
so, now we need to calculate the molality to substitute:
when the molality = moles NaCl / Kg of water
and when moles NaCl = mass / molar mass
= 2.5 g / 58 g/mol
= 0.043 mol
∴ Kg water = volume *density /1000
= 230 mL * 1 g/mL / 1000
= 0.23 Kg
∴ molality = 0.043 / 0.23 =0.187 M
by substitution:
T2-0°C = - 0.187 * 1.86
∴T2 = - 0.348 °C
Answer: (1). There are 0.0165 moles of gaseous arsine (AsH3) occupy 0.372 L at STP.
(2). The density of gaseous arsine is 3.45 g/L.
Explanation:
1). At STP the pressure is 1 atm and temperature is 273.15 K. So, using the ideal gas equation number of moles are calculated as follows.
PV = nRT
where,
P = pressure
V = volume
n = number of moles
R = gas constant = 0.0821 L atm/mol K
T = temperature
Substitute the values into above formula as follows.
2). As number of moles are also equal to mass of a substance divided by its molar mass.
So, number of moles of Arsine 
(molar mass = 77.95 g/mol) is as follows.
Density is the mass of substance divided by its volume. Hence, density of arsine is calculated as follows.
Thus, we can conclude that 0.0165 moles of gaseous arsine (AsH3) occupy 0.372 L at STP and the density of gaseous arsine is 3.45 g/L.
There is more carbon in the atmosphere
Answer: PCl₃O
Explanation:
1) The chemical formula tells the composition of a compound in terms of the ratio of number of atoms of each element that consitutes such compound.
2) You use the chemical symbol for each kind of atom (element) and subscripts to the right of each symbol to tell the number of atoms of each element.
3) For example, O₂ means two atoms of oxygen. Al₂O₃ means two atoms of aluminum and 3 atoms of oxygen.
4) Therefore, PCl₃O means a ratio 1 : 3 : 1 for phosphorus, chlorine, and oxygen.
Hence, PCl₃O is the chemical formula of your compound.
