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3 years ago

Calculate the average net charge on phenylalanine if it is in a solution that has a ph of 8.70.

1 answer:

5 0

Phenylalanine has two known pKa charges: 1.83 and 9.13. To determine their individual ionic dissociation charges at pH 10, the equation to be used is

pH = pKa + log [α/(1-α)]

At pKa 1.83:
10 = 1.83 + log [α₁/(1-α₁)]
α₁ = 0.99999

At pKa 9.13:
10 = 9.13 + log [α₂/(1-α₂)]
α₂ = 0.88114

Average Net Charge = 0.99999 + 0.88114 = 1.88

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What is a small description of a atom

steposvetlana [31]

Answer:

An atom is a particle of matter that uniquely defines achemical element. An atom consists of a central nucleus that is usually surrounded by one or more electrons. ... The nucleus is positively charged, and contains one or more relatively heavy particles known as protons and neutrons.

4 0

3 years ago

Read 2 more answers

A chemistry graduate student is given 125.mL of a 0.20M acetic acid HCH3CO2 solution. Acetic acid is a weak acid with =Ka×1.810−

Over [174]

Answer : The mass of sodium acetate is, 1.097 grams.

Explanation : Given,

The dissociation constant for acetic acid = $K_a=1.8\times 10^{-5}$

Concentration of acetic acid (weak acid)= 0.20 M

volume of solution = 125. mL

pH = 4.47

First we have to calculate the value of $pK_a$ .

The expression used for the calculation of $pK_a$ is,

$pK_a=-\log (K_a)$

Now put the value of $K_a$ in this expression, we get:

$pK_a=-\log (1.8\times 10^{-5})$

$pK_a=5-\log (1.8)$

$pK_a=4.74$

Now we have to calculate the concentration of sodium acetate (conjugate base or salt).

Using Henderson Hesselbach equation :

$pH=pK_a+\log \frac{[Salt]}{[Acid]}$

Now put all the given values in this expression, we get:

$4.47=4.74+\log (\frac{[Salt]}{0.20})$

$[Salt]=0.107M$

Now we have to calculate the mass of sodium acetate.

$\text{Concentration}=\frac{\text{Mass of }NaCH_3CO_2\times 1000}{\text{Molar mass of }NaCH_3CO_2\times \text{Volume of solution (in mL)}}$

$0.107M=\frac{\text{Mass of }NaCH_3CO_2\times 1000}{82g/mol\times 125mL}$

$\text{Mass of }NaCH_3CO_2=1.097g$

Therefore, the mass of sodium acetate is, 1.097 grams.

6 0

4 years ago

How many particles are there in 1.43 g of a molecular compound with a gram molecular mass of 233g

dalvyx [7]

<span>1.43g x (1 mole / 233g) x (6.022x10^23 particles / mole) = 3.70 x 10^ 21 particles</span>

7 0

3 years ago

what is the trend for the size as you go from Be to Mg to Ca? does the atomic size increase, decrease, or remain the same? how w

lys-0071 [83]

Answer:

the size of Ca is the greatest ,then Mg is the greater on size than Be

Explanation:

if you make the electron configuration for each of the elements, what is the main difference u gonna see ?

Be 4 1s2/2s2

Mg 12 1s2 /2s2 2p6/3s2

Ca 20 1s2 /2s2 2p6/3s2 3p6 3d/4s2

see that all the elements are in the same group but are in different period

u gonna see the last electron valance shell in Ca are too far from its nucleus but in Be the last electrons are too close and more attracted to the atom's nucleus , so the size of Ca is the biggest then Mg then Be

4 0

3 years ago

3. A gram food sample is burned completely in a calorimeter that contains 1000. of water The temperature of the water increases

lidiya [134]

The food has 23629.64 cal

<h3>Further explanation</h3>

Given

mass = 1000 g of water

temperature increases 23.65 * C

Required

The energy of the food

Solution

Heat absorbed by water :

Q = m . c . Δt

Q = 1000 g x 4.184 J/g°C x 23.65 °C

Q = 98951.6 J

1 Joules = 0.2388 Calories

98951.6 J = 23629.64 cal

3 0

3 years ago