Which of the following would have the greatest mass?

You are instructed to create 900. mL of a 0.29 M phosphate buffer with a pH of 7.8. You have phosphoric acid and the sodium salt

Aleksandr [31]

Answer:

B and C

Explanation:

When we have to do a buffer solution we always have to choose the reaction that has the pKa closer to the desired pH value. When we find the pKa values we will obtain:

$pKa_1=-Log[6.9x10^-^3]=2.16$

$pKa_2=-Log[6.2x10^-^8]=7.20$

$pKa_3=-Log[4.8x10^-^13]=12.31$

The closer value is pKa2 with a value of 7.2. Therefore we have to use the second reaction. In which $H_2PO_4^-^1$ is the acid and $HPO_4^-^2$ is the base. Therefore the answer for the first question is B and the answer for the second question is C.

8 0

3 years ago

What happens when atoms share electrons?

Anika [276]

When an atom shares electrons they form a covalent bond.

4 0

3 years ago

Which statements indicate what the fossil record suggests about evolution on Earth? Check all that apply.

Gennadij [26K]

The following are the statements, which indicates that the fossil record suggests about evolution on Earth:

1. Humans have only recently existed on Earth.

2. The organisms originally lived only in Earth's water.

3. The plants did not have flowers when dinosaurs existed.

The fossil remains have been discovered in the rocks of all the ages. The simplest organisms fossils are witnessed in the oldest rocks, and the fossils of more composite species are found in the newest rocks. This supports the theory of evolution suggested by Darwin, according to which the simple life forms slowly gets evolved into more composite ones.

6 0

3 years ago

Read 2 more answers

Assuming 100% dissociation, calculate the freezing point and boiling point (in °C) of a solution with 83.6 g of AgNO 3 in 1.00 k

Thepotemich [5.8K]

Answer:

Freezing point: - 1.83ºC

Boiling point: 100.50ºC

Explanation:

The freezing point and boiling point of solvents, when a solute is added, will change accordingly to the concentration of the solute particles.

The freezing point will decrease and the boiling point will increase. These are two colligative properties.

Find attached the file with the whole answer, as the site is not uploading the answer in here.

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3 0

4 years ago

Oh no! Igor stepped on a piece of glass on the sidewalk in front of

Helen [10]

Answer: The correct sequence for the series of event would be.

1. Igor's toe is being cut by the glass.

2. The wound surrounding the injury becomes infected with bacteria from Igor's foot.

3. Antibodies and circulating white blood cells stick to the bacteria creating a large complex in the lymph vessel.

4. The bacteria enter his lymph system and travel towards a lymph node.

5. The complex becomes trapped in a lymph node and is engulfed by a phagocyte.

6. The bacteria is destroyed.

Explanation:

Whenever there is any cut or wound in the body and body encounters invasion of the foreign materials it considers it as harmful pathogen.

These pathogens when enters the body it is considered as antigen, it then travels to the lymphatic system.

These bacterial complex is then killed by the phagocytes and digested by the body.

In this way the complex is killed and the bacteria is destroyed.

8 0

4 years ago