The answer is 62.00 g/mol.
Solution:
Knowing that the freezing point of water is 0°C, temperature change Δt is
Δt = 0C - (-1.23°C) = 1.23°C
Since the van 't Hoff factor i is essentially 1 for non-electrolytes dissolved in water, we calculate for the number of moles x of the compound dissolved from the equation
Δt = i Kf m
1.23°C = (1) (1.86°C kg mol-1) (x / 0.105 kg)
x = 0.069435 mol
Therefore, the molar mass of the solute is
molar mass = 4.305g / 0.069435mol = 62.00 g/mol
Answer:
a) HNO3 -> H+ + NO3- disassociation of Nitric Acid; to yield a Nitrate ion and a Proton, H+, or as a Hydronium ion H3O+
b) H2S04 -> Disassociation of Sulfuric Acid; simple way- 2H+ + SO4- -
c) H2S hydrogen sulphide in water is an acid; thus H+ HS- disassociation.
d) NaOH -> dissociation of Na+ + OH-; this is complete; sodium hydroxide is deliquescent, meaning it will draw water - EVEN from the air! Strong Base
e) Na2CO3 -> 2Na+ CO3- - Ionization of sodium carbonate - a salt
f) Na2S04 -> 2Na+ + SO4 - - ionization of sodium sulphate - a salt
g) NaCl -> Na+ + Cl- ionization of the salt, Sodium Chloride
Explanation:
Salts ionize at different rates; acids or bases dissociate; these are mostly strong acids and NaOH, a strong base.
The balanced chemical reaction for this would be written as:
2Mg + O2 = 2MgO
We use this reaction and the amount of the reactant given to calculate for the amount of magnesium oxide that is produced. We do as follows:
1.5 g Mg (1 mol / 24.31 g) ( 2 mol MgO / 2 mol Mg ) (40.30 g /1 mol ) = 2.49 g MgO produced