20 mL of an approximately 10% aqueous solution of ethylamine, CH3CH2NH2, is titrated with 0.3000 M aqueous HCl. Which indicator would be most suitable for this titration? The pKa of CH3CH2NH3+ is 10.75.
Answer:
Bromocresol green, color change from pH = 4.0 to 5.6
Explanation:
The equation for the reaction is as follows:
+ 
⇄ 
Given that concentration of = 10%
i.e 10 g of in 100 ml solution
molar mass = 45.08 g/mol
number of moles = 
= 0.222 mol
Molarity of = 0.222 × 
= 2.22 M
However, number of moles of in 20 mL can be determined as:
number of moles of = 20 mL × 2.22 M
= 
Concentration of = 
= 2.22 M
Similarly, The pKa Value of is given as 10.75
pKb value will be: 14 - pKa
= 14 - 10.75
= 3.25
Finally, the pH value at equivalence point is:
pH= ![\frac{1}{2}pKa - \frac{1}{2}pKb-\frac{1}{2}log[C]](https://tex.z-dn.net/?f=%5Cfrac%7B1%7D%7B2%7DpKa%20-%20%5Cfrac%7B1%7D%7B2%7DpKb-%5Cfrac%7B1%7D%7B2%7Dlog%5BC%5D)
pH = ![\frac{14}{2}-\frac{3.25}{2}-\frac{1}{2}log [2.22]](https://tex.z-dn.net/?f=%5Cfrac%7B14%7D%7B2%7D-%5Cfrac%7B3.25%7D%7B2%7D-%5Cfrac%7B1%7D%7B2%7Dlog%20%5B2.22%5D)
pH = 5.21
∴
The indicator that is best fit for the given titration is Bromocresol Green Color change from pH between 4.0 to 5.6.
Answer:
d. can be separated into components
it's the answer and i hope it helps you
The answer is NH4Cl!
Ionic bonding=cation + anion
- the cation ammonium (NH4) has a single electron in its valence shell, and Chlorine needs a single electron to fill its valence shell, and they stick together.
Covalent bond= involves the sharing of electron pairs between atoms
- present in Ammonium ion between Nitrogen and Hydrogen atoms
The most accurate way to measure a dry ingredient like flour, sugar or chocolate chips is in terms of its weight, which is measured in regular ounces.
Answer : Option B) Dependent variable.
Explanation : In this experiment the growth of pea plants is a dependent variable because, it depends upon the light which is available to it. As in the experiment James took two pea plants, and placed one in a dark closet and the other on a sunny window sill. Both were located in air-conditioned rooms. But the growth of the plant differs because of the light availability to it. Therefore, it is a dependent variable.
