Main advantages of DDT are the insecticide property and the knoledge about its chemical synthesis.
Explanation:
At that time in 1939 it was discovered that DDT have insecticide properties. It is a useful property because it allows inhibition of insects populations in large areas. Killing insects will reduce the diseases transmitted by them as typhus and malaria. More over you prevent the destruction of the agricultural crops by the harmful insects.
However the synthesis of the molecule was known way back in 1874. From that time it was plenty of time in which chemistry knowledge evolved so the synthesis at kilograms scale was implemented. High quantities of DDT molecule become available for the market so that in 1945 was available as agricultural insecticide.
It was discovered that DDT have bad effects for human health and also over time some insects developed resistance and their were not affected anymore by the molecule.
You may find the chemical structure of DDT in the attached figure.
Lean more:
about DDT
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Answer:
N = n× l
N = number of entities
n= moles
l = Avogadro's constant = 6.023 × 10^23
3.01 × 10^ 23 = n * 6.023 × 10^23
n = 3.01 × 10^23/6.023 × 10^23
n= 0.5moles
Molar mass = mass/ number of moles
Molar mass = 56
mass = 56 × 0.5
= 28g
Hope this helps.
Answer:
4.00 is the pH of the mixture
Explanation:
The ethyl amine reacts with HNO3 as follows:
C2H5NH2 + HNO3 → C2H5NH3⁺ + NO3⁻
To solve this question we need to find the moles of ethyl amine and the moles of HNO3:
<em>Moles C2H5NH2:</em>
0.0500L * (0.100mol/L) = 0.00500 moles ethyl amine
<em>Moles HNO3:</em>
0.201L * (0.025mol/L) = 0.005025 moles HNO3
That means HNO3 is in excess. The moles in excess are:
0.005025 moles HNO3 - 0.00500 moles ethyl amine =
2.5x10⁻⁵ moles HNO₃
In 50 + 201mL = 251mL = 0.251L:
2.5x10⁻⁵ moles HNO₃ / 0.251L = 9.96x10⁻⁵M = [H+]
As pH = -log [H+]
pH = -log 9.96x10⁻⁵M
pH = 4.00 is the pH of the mixture