A umidade absoluta é a medida do vapor de água (umidade) no ar, independentemente da temperatura. É expresso como gramas de umidade por metro cúbico de ar (g / m3).
Answer:
621.41 grams
Explanation:
First of all, to find the mass. You have to use the molar mass of AlBr3 to convert from moles to mass.
Second of all, find the molar mass of AlBr3.
Al = 27.0 amu
Br = 79.9 amu
They are 3 bromine atoms and 1 aluminum atom.
So you do this
27.0 + 79.9(3) = 266.7
The molar mass is 266.7 g/mol
Third of all, use dimensional analysis to show your work.
2.33 moles of AlBr3 * 266.7 g/mol / 1 mol
Moles cancel out.
2.33 x 266.7 = 621.411
Your teacher though said to round digits after the decimal point instead of using sig figs.
621.411 rounds to 621.41
So the final answer is 621.41 grams(don't forger the units).
The substance formula is just AlBr3.
That's all.
Hope it helped!
Answer:
Enthalpy Change when 1 mole CaCl₂ dissolves
= - 81.13 kj/mole
Explanation:
Given information
Mass of CaCl₂ = 23.6 g
Temperature changes from 25.0°C to 38.7°C
Heat capacity of solution & calorimeter (C) = 1258 J/°C
We know Q = C x ΔT
⇒ Heat released = 1258 x (38.7 - 25)
= 1.7234 x 10⁴ J
= 17.2 Kilo-joule
Thus 23.6 g is equivalent to 1.7234 x 10⁴ J or 17.2 Kilo-joule of heat energy
Molar mass of calcium chloride (110.98)
Enthalpy Change when 1 mole CaCl₂ dissolves
= 
Answer:
3.11 mol/kg
Explanation:
Molality M = number of moles of solute, n/mass of solvent, m
To calculate the number of moles of glycerol (C₃H₈O₃) in 22.75 g of glycerol, we find its molar (molecular) mass, M',
So, M' = 3 × atomic mass of carbon + 8 × atomic mass hydrogen + 3 × atomic mass of oxygen
= 3 × 12 g/mol + 8 × 1 g/mol + 3 × 16 g/mol = 36 g/mol + 8 g/mol + 48 g/mol = 92 g/mol.
So, number of moles of glycerol, n = m'/M' where m' = mass of glycerol = 22.75 g and M' = molecular mass of glycerol = 92 g/mol
So, n = m'/M'
n = 22.75 g/92 g/mol
n = 0.247 mol
So, the molality of the solution M = n/m
Since m = mass of ethanol = 79.6 g = 0.0796 kg, substituting the value of n into the equation, we have
M = 0.247 mol/0.0796 kg
M = 3.11 mol/kg
So, the molality of the solution is 3.11 mol/kg.
