Answer:
Aqueous NaOH: <u>soluble
</u>
Aqueous NaHCO₃: <u>insoluble</u>
Aqueous Na₂CO₃: <u>soluble</u>
Explanation:
The organic acid is insoluble. Its salt (ionic) is soluble.
The important principle is:
If you have two acids in a flask, the stronger acid (smaller pKₐ) will protonate the weaker one. The stronger acid will become ionic and therefore more soluble.
1. In NaOH
Let's write the formula for 4-nitrobenzoic acid as HA.
The equation for the reaction is
HA + OH⁻ ⇌ A⁻ + H₂O
pKₐ: 7.15 15.7
HA is the stronger acid. It will protonate the hydroxide ion and be converted to the soluble 4-nitrobenzoate ion.
4-Nitrophenol is soluble in NaOH.
2. In NaHCO₃
HA + HCO₃⁻ ⇌ A⁻ + H₂CO₃
pKₐ: 7.15 6.36
HCO₃⁻ is the stronger acid. It will protonate 4-nitrophenol.
4-Nitrobenzoic acid is insoluble in NaHCO₃.
3. In Na₂CO₃
HA + CO₃²⁻ ⇌ A⁻ + H₂CO₃
pKₐ: 7.15 10.33
HA is the stronger acid. It will protonate the carbonate ion.
4-Nitrophenol is soluble in Na₂CO₃.
question 1
moles = mass/molar mass of Al(OH)3
convert Kg to g
that is 1.09 x 1000=1090g
moles is therefore=1090g/78(molar mass of Al(OH)3)= 13.974 moles
question 2
moles=2.55g/327.2(molar mass of Pb(CO3)2= 7.79 x 10^-3 moles
from avogadro constant
1moles=6.02 x10^23 formula units
what about 7.79 x 10 ^-3
={(7.79 x 10^-3)moles x ( 6.02 x10^23)} /1 mole=4.69 x10^21 formula units
0.81 moles
Explanation:
cobalt chloride when dissolved in water dissociate into cobalt and chloride ions as shown;
CoCl₂ (s) → [Co²⁺](aq) + 2[Cl⁻] (aq)
The mole ratio between CoCl₂ and [Co²⁺] is 1 ; 1 while the mole ratio between CoCl₂ and [Cl⁻] is 1 : 2
Therefore; 0.27 moles of CoCl₂ will form;
(1 * 0.27) = 0.27 moles of [Co²⁺] ions
(2 * 0.27) = 0.54 moles of [Cl⁻] ions
Total moles of dissociated ions are;
0.27 + 0.54
= 0.81 moles
Answer: Potassium is 39.10 g/mol
Explanation: The numbers below the element are the molar mass.
Scientist believe that about 25 of the known elements are essential to life. Just four of these - Carbon (C), Oxygen (O), Hydrogen (H), and Nitrogen (N), - make up about 96% of the human body.
These four elements are found in the basic structure of all biochemical molecules. For example, Glucose is a carbohydrate and it's molecular formula is C6H12O6 - each molecule of glucose is made up of 6 Carbon atoms, 12 Hydrogen atoms and 6 oxygen atoms.
The other elements found can be divided into two main groups - major elements and trace elements.
The human body functions as a result of a large number of the chemical reactions involving compounds of a of these elements.