Answer:
Two characteristics that make water a good choice for the recrystallization solvent for benzoic acid are
- Low solubility for benzoic acid at room temperature
- Less expensive
Explanation:
Characteristics of a Good Recrystallization Solvent:
- Cheap.
- High volatility.
- No reaction with substrate to be made pure.
- Insoluble impurities should not be dissolced by the olvent at all temperatures.
- At room temperature the solvent should have high solubility for soluble impurities well
- At room temperature the substance to be purified should be insoluble in the solvent.
As such water has both low solubility for benzoic acid at room temperature and water is cheap or readily available
Answer:
The effective nuclear charge (often symbolized as Zeff or Z*) is the net positive charge experienced by an electron in a multi-electron atom. The term “effective” is used because the shielding effect of negatively charged electrons prevents higher orbital electrons from experiencing the full nuclear charge.
Explanation:
From the gas law, PV=nRT we can say that P(pressure), V(volume) and T (temperature) are related to each other. The initial volume of sample is 408 ml
Given that initial volume of the sample = V1
initial pressure of the sample = 0.92atm
initial temperature of the sample = 23.2oC
Final pressure of the sample = 1.3atm
Final temperature of the sample = 40.1 oC
Final volume of the sample = 500ml = 0.5L
Using the relation P1V1/T1 = P2V2/T2
V1 = 1.3x0.5x23.2/40.1x0.92 = 15.08/36.892 = 0.408
Hence the initial volume of sample = 408 ml
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Answer:
74.10g/mol
Explanation:
The mass of one mole of Ca(OH)₂ is the molar mass of the compound.
To solve this problem, we add the atomic masses of the species in the compound;
Atomic mass of Ca = 40.078g/mol
O = 15.9994g/mol
H = 1.0079g/mol
So;
Molar mass = 40.078 + 2(15.9994 +1.0079 ) = 74.10g/mol
Hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), sulfur hexafluoride (SF6) and nitrogen trifluoride (NF3).
