Name the following bases.

As a technician in a large pharmaceutical research firm, you need to produce 250. mL of a potassium dihydrogen phosphate buffer

Reika [66]

Answer:

We will need 147.772 mL of KH2PO4 to make this solution

Explanation:

For this case we can give the following equation:

H2PO4 - ⇄ H+ + HPO42-

With following pH- equation:

pH = pKa + log [HPO42-]/[H2PO4-]

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

-0.16 = log [HPO42-]/[H2PO4-]

10^-0.16 = [HPO42-]/[H2PO4-]

0.6918 = [HPO42-]/[H2PO4-]

Let's say the volume of HPO42-= x then the volume of H2PO4- will be 250 mL - x

Since both have a concentration of 1M = 1 mol /L

If we plug this in the equation 0.6918 = [HPO42-]/[H2PO4-]

0.6918 = x / (250 - x)

0.6918*250 - 0.6918x = x

172.95 = 1.6918x

x = 102.228 mL

The volume of HPO42- = 102.228 mL

Then the volume of H2PO4- = 250 - 102.228 = 147.772 mL

To control this we can plug this in the pH equation

7.05 = 7.21 + log [HPO42-]/[H2PO4-]

7.05= 7.21 + log (102.228 / 147.772) = 7.05

We will need 147.772 mL of KH2PO4 to make this solution

3 0

3 years ago

Can someone please explain this to me? I need help

Vladimir [108]

Answer:

The order would be: X-Rays, Visible Light, and Infrared Waves.

X-Rays have the shortest wavelength out of all three, then Visible Light, and Infrared Waves have the longest wavelength of the three.

Explanation:

So basically, the LONGER the wavelength, the lower the energy. and the SHORTER the wavelength, the higher the energy. For example, Radio waves are the WEAKEST out of all the types of waves because they have the LONGEST wavelengths. Gamma Rays are the STRONGEST out of all the types of waves because they have the SHORTEST wavelengths. So Radio Waves have the lowest energy, and Gamma Rays have the highest energy.

Here is a list of all the types of waves in order from shortest wavelength to longest wavelengths:

Gamma Rays (Shortest Wavelengths, High Energy), then X-Rays would be the second strongest, then Ultraviolet waves, then Visible Light, then Infrared waves, then Microwaves, and lastly Radio Waves (Longest Wavelengths, Low Energy).

6 0

3 years ago

Read 2 more answers

A 31.1 g wafer of pure gold, initially at 69.3 _c, is submerged into 64.2 g of water at 27.8 _c in an insulated container. what

KIM [24]

Given:
Ma = 31.1 g, the mass of gold
Ta = 69.3 °C, the initial temperature of gold
Mw = 64.2 g, the mass of water
Tw = 27.8 °C, the initial temperature of water

Because the container is insulated, no heat is lost to the surroundings.
Let T °C be the final temperature.

From tables, obtain
Ca = 0.129 J/(g-°C), the specific heat of gold
Cw = 4.18 J/(g-°C), the specific heat of water

At equilibrium, heat lost by the gold - heat gained by the water.
Heat lost by the gold is
Qa = Ma*Ca*(T - Ta)
= (31.1 g)*(0.129 J/(g-°C)(*(69.3 - T °C)-
= 4.0119(69.3 - T) j
Heat gained by the water is
Qw = Mw*Cw*(T-Tw)
= (64.2 g)*(4.18 J/(g-°C))*(T - 27.8 °C)
= 268.356(T - 27.8)

Equate Qa and Qw.
268.356(T - 27.8) = 4.0119(69.3 - T)
272.3679T = 7738.32
T = 28.41 °C

Answer: 28.4 °C

3 0

3 years ago

Read 2 more answers

In a chemical equation, the arrow points towards what?

stepan [7]

The arrow doesn’t “point” to anything really, it means that the reactants form (or change) into the products.

3 0

3 years ago

Read 2 more answers

What careers use scientific notation?

Tpy6a [65]

Micro-Biologist &