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mrs_skeptik [129]
3 years ago
15

how many milliliters of a stock solution of 2.00M KNO3 would you need to prepare 100.0mL of 0.150M KNO3?

Chemistry
1 answer:
larisa86 [58]3 years ago
3 0
The answer is 7.5 ml
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The pH of an acid solution is 5.82. Calculate the Ka for the monoprotic acid. The initial acid concentration is 0.010 M.
blagie [28]

Answer:

The answer is

<h3>Ka = 2.29 \times  {10}^{ - 14} moldm^{ - 3}</h3>

Explanation:

The Ka of an acid when given the pH and concentration can be found by

<h3>pH =  -  \frac{1}{2}  log(Ka)  -  \frac{1}{2}  log(c)</h3>

where

c is the concentration of the acid

From the question

pH = 5.82

c = 0.010 M

Substitute the values into the above formula and solve for Ka

We have

<h3>5.82 =   - \frac{1}{2}  log(Ka)  -  \frac{1}{2}  log(0.010)</h3><h3 /><h3>-  \frac{1}{2}  log(Ka)  = 5.82 + 1</h3><h3 /><h3>-  \frac{1}{2}  log(Ka)  = 6.82</h3>

Multiply through by - 2

<h3>log(Ka)  =  - 13.64</h3>

Find antilog of both sides

We have the final answer as

<h3>Ka = 2.29 \times  {10}^{ - 14} moldm^{ - 3}</h3>

Hope this helps you

8 0
3 years ago
which of the following amino acids are used to measure the protein concentration by UV? A. His B. Pro C. Trp D. Phe E. Tyr
Goryan [66]

Answer:

C. Trp D. Phe E. Tyr

Explanation:

The concentration of a protein has a direct relation with absorbance of the protein in a UV spectrophotometer. The formula which relates concentration with absorbance is described as under:

                A = ∈ x c x l

where, A = Absorbance

            ∈ = Molar extinction co-efficient

            c  = Concentration of absorbing species i.e. protein

             l  = Path length of light

       

Tryptophan (Trp), phenylalanine (Phe ) and tyrosine (Tyr) are three aromatic amino acids which are used to measure protein concentration by UV. It is mainly because of tryptophan (Trp), protein absorbs at 280 nm which gives us an idea of protein concentration during UV spectroscopy.

The table depicting the wavelength at which these amino acids absorb and their respective molar extinction coefficient is as under:

Amino acid                Wavelength            Molar extinction co-efficient (∈)

Tryptophan                     282 nm                        5690

Tyrosine                          274 nm                        1280

Phenylalanine                 257 nm                        570

In view of table above, we can easily see that Molar extinction co-efficient (∈) of Tryptophan is highest amongst all these 3 amino acids that is why it dominates while measuring concentration.

7 0
3 years ago
Choose two ways carbon returns to nature from animals
SVEN [57.7K]

Answer:

its D and C I did the test

8 0
3 years ago
Be sure to answer all parts. The percent by mass of bicarbonate (HCO3−) in a certain Alka-Seltzer product is 32.5 percent. Calcu
pochemuha

Answer : The volume of CO_2 will be, 514.11 ml

Explanation :

The balanced chemical reaction will be,

HCO_3^-+HCl\rightarrow Cl^-+H_2O+CO_2

First we have to calculate the  mass of HCO_3^- in tablet.

\text{Mass of }HCO_3^-\text{ in tablet}=32.5\% \times 3.79g=\frac{32.5}{100}\times 3.79g=1.23175g

Now we have to calculate the moles of HCO_3^-.

Molar mass of HCO_3^- = 1 + 12 + 3(16) = 61 g/mole

\text{Moles of }HCO_3^-=\frac{\text{Mass of }HCO_3^-}{\text{Molar mass of }HCO_3^-}=\frac{1.23175g}{61g/mole}=0.0202moles

Now we have to calculate the moles of CO_2.

From the balanced chemical reaction, we conclude that

As, 1 mole of HCO_3^- react to give 1 mole of CO_2

So, 0.0202 mole of HCO_3^- react to give 0.0202 mole of CO_2

The moles of CO_2 = 0.0202 mole

Now we have to calculate the volume of CO_2 by using ideal gas equation.

PV=nRT

where,

P = pressure of gas = 1.00 atm

V = volume of gas = ?

T = temperature of gas = 37^oC=273+37=310K

n = number of moles of gas = 0.0202 mole

R = gas constant = 0.0821 L.atm/mole.K

Now put all the given values in the ideal gas equation, we get :

(1.00atm)\times V=0.0202 mole\times (0.0821L.atm/mole.K)\times (310K)

V=0.51411L=514.11ml

Therefore, the volume of CO_2 will be, 514.11 ml

6 0
2 years ago
Aspirin can be made in the laboratory by reacting acetic anhydride (c4h6o3) with salicylic acid (c7h6o3) to form aspirin (c9h8o4
Temka [501]
V(C₄H₆O₃) = 5.00 mL.
d(C₄H₆O₃) = 1.08 g/mL.
m(C₄H₆O₃) = V(C₄H₆O₃) · d(C₄H₆O₃).
m(C₄H₆O₃) = 5.00 mL · 1.08 g/mL.
m(C₄H₆O₃) = 5.4 g.
n(C₄H₆O₃) = m(C₄H₆O₃) ÷ M(C₄H₆O₃).
n(C₄H₆O₃) = 5.4 g ÷ 102 g/mol.
n(C₄H₆O₃) = 0.0529 mol.
n(C₇H₆O₃) = 2.08 g ÷ 138.1 g/mol.
n(C₇H₆O₃) = 0.015 mol; limiting reactant.
From chemical reaction: n(C₄H₆O₃) : n(C₉H₈O₄) = 1 : 1.
n(C₉H₈O₄) = 0.015 mol.
m(C₉H₈O₄) = 0.015 mol · 180.16 g/mol.
m(C₉H₈O₄) = 2.71 g; theoretical yield.
percent yield od aspirine = 2.57 g ÷ 2.71 g · 100% = 94.83%.

7 0
3 years ago
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