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ludmilkaskok [199]
3 years ago
13

Ou have a 5 ml sample of a protein in 0.5 m nacl. you place the protein/salt sample inside dialysis tubing (see fig. 2-14) and p

lace the bag in a large beaker of distilled water. if your goal is to remove as much nacl from the sample as possible, which would be more effective: (1) placing the dialysis bag in 4 l of distilled wa- ter for 12 h, or (2) placing the bag in 1 l of distilled water for 6 h and then in another 1 l of fresh distilled water for another 6 h
Chemistry
1 answer:
Oduvanchick [21]3 years ago
4 0

Answer:

Procedure (2)  

Explanation:

Assume the dialyses come to equilibrium in the allotted times.

Procedure (1)

If you are dialyzing 5 mL of sample against 4 L of water, the concentration of NaCl will be decreased by a factor of

\dfrac{5}{4000} = \dfrac{1}{800}

Procedure (2)

For the first dialysis, the factor is

\dfrac{5}{1000} = \dfrac{1}{200}

After a second dialysis, the original concentration of NaCl will be reduced by a factor of  

\dfrac{1}{200} \times \dfrac{1}{200} = \dfrac{1}{40000}

Procedure (2) is more efficient by a factor of  

\dfrac{40000}{800} = \mathbf{50}

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The activation barrier for the hydrolysis of sucrose into glucose and fructose is 108 kJ/mol. Part A If an enzyme increases the
emmasim [6.3K]

Answer:

The barrier has to be 34.23 kJ/mol lower when the sucrose is in the active site of the enzyme

Explanation:

From the given information:

The activation barrier for the hydrolysis of sucrose into glucose and fructose is 108 kJ/mol.

In this  same concentration for the glucose and fructose; the reaction rate can be calculated by the rate factor which can be illustrated from the Arrhenius equation;

Rate factor in the absence of catalyst:

k_1= A*e^{^{^{ \dfrac {- Ea_1}{RT}}

Rate factor in the presence of catalyst:

k_2= A*e^{^{^{ \dfrac {- Ea_2}{RT}}

Assuming the catalyzed reaction and the uncatalyzed reaction are  taking place at the same temperature :

Then;

the ratio of the rate factors can be expressed as:

\dfrac{k_2}{k_1}={  \dfrac {e^{ \dfrac {- Ea_2}{RT} }} { e^{ \dfrac {- Ea_1}{RT} }}

\dfrac{k_2}{k_1}={  \dfrac {e^{[  Ea_1 - Ea_2 ] }}{RT} }}

Thus;

Ea_1-Ea_2 = RT In \dfrac{k_2}{k_1}

Let say the assumed temperature = 25° C

= (25+ 273)K

= 298 K

Then ;

Ea_1-Ea_2 = 8.314 \  J/mol/K * 298 \ K *  In (10^6)

Ea_1-Ea_2 = 34228.92 \ J/mol

\mathbf{Ea_1-Ea_2 = 34.23 \ kJ/mol}

The barrier has to be 34.23 kJ/mol lower when the sucrose is in the active site of the enzyme

8 0
3 years ago
Which body system provides protection of the brain and the spinal cord?
gogolik [260]

Answer:

The bones of the skull and spinal column

Explanation:

The central nervous system is better protected than any other system or organ in the body. Its main line of defense is the bones of the skull and spinal column, which create a hard physical barrier to injury.

8 0
3 years ago
Read 2 more answers
Vinegar is a solution of acetic acid (the solute) in water (the solvent) with a solution density of 1010 g/L. If vinegar is 0.80
Damm [24]

Answer:

4.8 %

Explanation:

We are asked the concentration in % by mass, given the molarity of the solution and its density.

0.8 molar solution means that we have 0.80 moles of acetic acid in 1 liter of solution. If we convert the moles of acetic acid to grams, and the 1 liter solution to grams, since we are given the density of solution, we will have the values necessary to calculate the % by mass:

MW acetic acid = 60.0 g/mol

mass acetic acid (the solute) = 0.80 mol x 60 g / mol = 48.00 g

mass of solution = 1000 cm³ x 1.010 g/ cm³      (1l= 1000 cm³)

                            = 1010 g

% (by mass) = 48.00 g/ 1010 g  x 100 = 4.8 %

6 0
3 years ago
For each pair, choose the compound with the smaller lattice energy, and explain your choice: (b) K₂O or K₂S.
dlinn [17]

the compound with the smaller lattice energy is potassium sulphide here the size of the molecule play a important role

The quantity of energy released by the electrostatic attraction of oppositely charged ions is known as lattice energy (L.E). The ion's size and charge affect the lattice energy.

lattice energy is inversely proportional to   size of ion and directly proportional to charge of the ion. They are each charged equally that is plus two and minus two However, because the Sulphur is larger in size  and the oxygen is lesser in this case, The lattice energy of potassium oxide is larger  the lattice energy of potassium sulphide  is smaller.

To learn more about lattice energy :

brainly.com/question/18222315

#SPJ4

5 0
1 year ago
_Li + __F2 → _LIF<br> How do I balance this?
Semmy [17]

Answer:

 2Li   +   F₂    →    2LiF

Explanation:

The reaction expression is given as:

          Li   +   F₂    →     LiF

We are to balance the expression. In that case, the number of atoms on both sides of the expression must be the same.

 Let use a mathematical approach to solve this problem;

  Assign variables a,b and c as the coefficients that will balance the expression:

             aLi   +  bF₂    →     cLiF

Conserving Li: a  = c

                   F:  2b  = c

          let a = 1, c  = 1 and b  = \frac{1}{2}  

  Multiply through by 2;

        a  = 2, b = 1 and c  = 2

               2Li   +   F₂    →    2LiF

 

5 0
3 years ago
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