Answer:
b) pH = 9.25
Explanation:
- NH4+(aq) + H2O(l) ↔ NH3(aq) + H3O+(aq)
- NH3 + H2O ↔ NH4+ + OH-
- 2 H2O ↔ H3O+ + OH-
⇒ Kb = [ NH4+ ] * [ OH- ] / [ NH3 ] = 1.86 E-5......from literature
mass balance NH4+:
⇒ M NH4+ = [ NH4+ ] - [ OH- ]
∴ [ NH3 ] ≅ M NH4+ = 0.26 M
⇒ Kb = (( 0.26 + [ OH- ] )) * [ OH- ] / 0.26 = 1.86 E-5
⇒ 0.26 [ OH-] + [ OH- ]² = 4.836 E-6
⇒ [ OH- ]² + 0.26 [ OH- ] - 4.836 E-6 = 0
⇒ [ OH- ] = 1.859 E-5 M
⇒ pOH = - Log ( 1.859 E-5 )
⇒ pOH = 4.7305
⇒ pH = 14 - pOH = 9.269
The three situations can be described as
a) If we have two white powders and wish to distinguish between the two : the combinations can be sugar / salt or sugar / baking soda or salt / baking soda
all are kitchen items so we can either taste them
or in case of baking soda we can add it in water and it will produce brisk effervescence.
b) IF we have to distinguish in a given set of two transparent liquids which appear to be water (example water and vinegar)
we can identify them with the taste
we can identify them based on pH (vinegar will be acidic)
c) We have to find adulteration in a given sample of food
like adulteration in milk
for example presence of soap in milk
We can add indicator like phenolphthalein which will bring a pink colour in milk if soap is present
Answer:
Neutron
Explanation:
Neutron, neutral subatomic particle that is a constituent of every atomic nucleus except ordinary hydrogen. It has no electric charge and a rest mass equal to 1.67493 × 10−27 kg—marginally greater than that of the proton but nearly 1,839 times greater than that of the electron.
Oxygen is the second. The first is nitrogen which makes up 78% of air. Oxygen makes up 21% of air.
