Calculate the mass percent of water in Sodium sulfate decahydrate, In separating

Question

Calculate the mass percent of water in Sodium sulfate decahydrate, In separating NH_4Cl from the mixture, you had to heat it strongly in the fume hood until all the NH_4Cl had been converted to gas (smoke) and removed. a. Why did you use fume hood for this experiment? b. What name is given to this process of removing solid by heating strongly? Explain what you understand by a. Stationary phase b. Mobile phase c. R_4 Calculate the distance moved by a compound if the R_f value is 0.66 under a condition in which the solvent had moved 9.8 cm. What are the two factors used to identity a substance in our paper chromatography experiment? What is the empirical formula of a compound formed by burning 0.510 g of Phosphorus in oxygen to form 1.155 g of phosphorus oxide? Atomic masses of P and O are 31 arum and 16 arum respectively.

Explanation / Answer

6) Na2SO4 · 10H2O molar mass: 322.186 g/mole

Water molecular wt = 18.01528 g/mol

Mass water present in Na2SO4 · 10H2O = 10 x 18.0153 g/mol =180.153 g/mol

Mass percent of water = (mass of water/ total mass) x 100 = 55.9 %

7) ammonium chloride NH4Cl decomposes into the gases ammonia (NH3) and hydrogen chloride (HCl).

NH4Cl ----> NH3 (g) + HCl (g)

a) both NH3 and HCl gases are toxic, so it is recommended to use hood not to in contact with the fumes of NH3 and HCl.
b) this process is a decomposition of NH4Cl, so it called a decomposition process.

8) a) Stationary phase where the components of mixtures are separated by the relative attraction of the components
on its surface.
b) mobile phase: a mobile phase (a liquid or gas) passes over the stationary phase in a chromatographic technique.
c) Rf: It is the fraction of an analyte in the mobile phase
Rf= it is the ratio of migration distance of substance to the migration distance of the solvent front.

Rf = (migration distance of substance)/ (migration distance of solvent front)

9) we have Rf = 0.66 ; and migration distance of solvent front = 9.8 cm

Rf = (migration distance of compound)/ (migration distance of solvent front)
0.66 = migration distance of compound/9.8 cm

migration distance of compound = 0.66 x 9.8 cm = 6.468 cm

10) Solubility and adsorption are the two main factors in the paper chromotography.

11) what is empiriacal formula of a compound formed by burning 0.510 g of phosphorous in oxygen to form 1.155 g of
phosphorous oxide. atomic masses of P and O are 31 amu and 16 amu respectively

Calculate moles of P and O:

    P 0.510 g / 31 g/mol = 0.01645 mol
    O (1.155-0.51) g / 16.00 g/mol = 0.040 mol

2) Determine lowest whole-number ratio:

    P 0.01645 mol / 0.01645 mol = 1
    O 0.040 mol / 0.01645mol = 2.45 ~ 2.5

3) Determine empirical formula:

    P2O5

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