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3 years ago

What can you conclude about the relative concentrations of ch3nh2 and ch3nh3cl in this buffer? for ch3nh2, pkb = 3.36?

1 answer:

8 0

POH = pKb + log [salt] / [base] ---> Basic Buffer
and pH = 14 - pOH

to predict the relative concentrations of the buffer components you need to know both pKb and pH...

While in this case only pKb is given and the pH of buffer is not given. So, nothing can be concluded about the relative concentrations of CH₃NH₂ and CH₃NH₃Cl

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Which properties do not change the composition of a substance?

Nina [5.8K]

Answer:

Physical Properties

Explanation:

PHYSICAL PROPERTY

7 0

4 years ago

A chemist measures the energy change

Flauer [41]

Answer:

For (1): The correct option is (a)

For (2): The correct option is (a) and 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts.

Explanation:

There are 2 types of reactions that are classified based on enthalpy change:

Endothermic reactions: These are the reactions where heat is absorbed by the reaction. The change in enthalpy of the reaction, $\Delta H_{rxn}$ is positive for these reactions.

Exothermic reactions: These are the reactions where heat is released by the reaction. The change in enthalpy of the reaction, $\Delta H_{rxn}$ is negative for these reactions.

For (1):

For the given chemical reaction:

$2NH_3(g)\rightarrow N_2(g)+3H_2(g);Delta H=160kJ$

As the change in enthalpy or heat of the reaction is positive. Thus, the reaction is an endothermic reaction because heat is absorbed by the reaction.

For (2):

When ammonia reacts, some amount of heat will be absorbed by the reaction. Thus, we can say the heat will be absorbed.

The number of moles is calculated by using the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ ......(1)

Given mass of ammonia = 70.9 g

Molar mass of ammonia = 17 g/mol

Using equation 1:

$\text{Moles of ammonia}=\frac{70.9g}{17g/mol}=4.17mol$

By stoichiometry of the reaction:

If 2 mole of ammonia reacts, the heat absorbed is 160 kJ

So, if 4.17 moles of ammonia reacts, the heat absorbed will be = $\frac{160kJ}{2mol}\times 4.17mol=333.6kJ$

Hence, 333.6 kJ of heat will be absorbed when 70.9 g of ammonia reacts

8 0

3 years ago

3. From the following formula, calculate the quantities required to make 5 lb o hydrophilic ointment. Methylparaben 0.25 g Propy

adell [148]

The given question is incomplete. The complete question is as follows.

From the following formula, calculate the quantities required for each of the following ingredients to make 5 lb. (avoir) of hydrophilic ointment. All values to be in g, do not include units in your submitted answer; use no more than 3 decimal places. Convert using 1 lb = 454 g. Note: all values done by mass, including the water, so this is not a q.s situation (volume is irrelevant).

Methylparaben 0.25 g

Propylparaben 0.15 g

Sodium Lauryl Sulfate 10 g

Propylene Glycol 120 g

Stearyl Alcohol 240 g

White Petrolatum 250 g

Purified Water, to make 1000 g

Explanation:

For the given quantities, the sum is 620.4 g. Now, amount of purified water (to make 1000 g of ointment) is as follows.

1000 g - 620.4 g

= 379.6 g

Now, to make 5 lb we will calculate the quantities as follows.

Formula weight = 1000 g

Therefore, desired quantity is as follows.

5 lb = 5 x 454 g

= 2270 g

Hence, this means the factor is calculated as follows.

$\frac{2270 g}{1000 g}$

= 2.27

Now, we will calculate the quantity of each ingredient using factor 2.27 as follows.

Methylparaben = 0.25 g x 2.27 = 0.5675 g

Propylparaben = 0.15 g x 2.27 = 0.3405 g

Sodium Lauryl Sulfate = 10 g x 2.27 = 22.7 g

Propylene Glycol = 120 g x 2.27 = 272.4 g

Stearyl Alcohol = 240 g x 2.27 = 544.8 g

White Petrolatum = 250 g x 2.27 = 567.5 g

Purified Water = 379.6 g x 2.27 = 861.692 g

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3 years ago

Ionizing radiation causes cancer by Select one: a. forming ions, causing reactions that mutate DNA b. forming ions, causing reac

Pachacha [2.7K]

Answer:

a. forming ions, causing reactions that mutate DNA

Explanation:

Ionizing radiation is a type of energy released by atoms in the form of electromagnetic waves or particles. The spontaneous decay of atoms is called radioactivity, and the surplus energy emitted is a form of ionizing radiation. The unstable elements that decay and emit ionizing radiation are called radionuclides.

Exposure of a human being to certain doses of ionizing radiation can cause irreparable changes in the structure of their DNA, that is, in the genes that control the function of cells, and therefore cause a series of changes that can lead to a cancer.

3 0

3 years ago

Explain how the atom is electrically neutral, having an equal number of protons and electrons.

lord [1]

Answer:

A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other and atom become neutral.

Explanation:

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. In other words we can say that negative and positive charges are equal in magnitude and cancel the each other and atom become neutral. For example if neutral atom has 6 protons than it must have 6 electrons. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.

For example

The carbon have six protons and six neutrons so its atomic mass is 12 amu and atomic number is six.

5 0

3 years ago