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serious [3.7K]
3 years ago
12

g Calculate the pOH of a solution that results from mixing 23.3 mL of 0.16 M trimethylamine ((CH3)3N) with 44.1 mL of 0.15 M (CH

3NH3Cl. The Kb value for (CH3)3N is 6.5 x 10-5.
Chemistry
1 answer:
hichkok12 [17]3 years ago
6 0

Answer:

pOH = 5.961

Explanation:

To find the pH of a weak base we can use Henderson-Hasselbalch equation for weak bases:

pOH = pKb + log [(CH₃)₃NHCl] / [(CH₃)₃N]

<em>Where pKb is -log Kb = 4.187 and [] could be taken as moles of each specie.</em>

<em />

<em>Moles (CH₃)₃NHCl:</em>

0.0441L * (0.15mol/L) = 6.615x10⁻³moles

<em>Moles (CH₃)₃N:</em>

0.0233L * (0.16mol/L) = 3.728x10⁻³moles

And pOH is:

pOH = pKb + log [(CH₃)₃NHCl] / [(CH₃)₃N]

pOH = 4.187 + log [6.615x10⁻³moles] / [3.728x10⁻³moles]

<h3>pOH = 5.961</h3>

<em />

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A solution was made by dissolving 5.10 mg of hemoglobin in water to give a final volume of 1.00 ml. the osmotic pressure of this
Assoli18 [71]

The molecular weight of hemoglobin can be calculated using osmotic pressure

Osmotic pressure is a colligative property and it depends on molarity as

πV = nRT

where

π = osmotic pressure

V = volume = 1mL = 0.001 L

n = moles

R = gas constant = 0.0821 L atm / mol K

T = temperature = 25°C = 25 + 273 K = 298 K

Putting values we will get value of moles

moles=\frac{\pi V}{RT}=\frac{0.00195X0.001}{0.0821X298}mol

we know that

moles=\frac{mass}{molarmass}

Therefore

molarmass=\frac{mass}{moles}=\frac{5.10X10^{-3}g}{7.97X10^{-8}}=6.399X10^{4}g

5 0
2 years ago
When water vapor condenses, how much heat energy will be released into the atmosphere?
Leona [35]
<span><span>When water vapor condenses, 2260 joules/gram heat energy will be released into the atmosphere.

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2 years ago
Omg GUYS I NEED HELPPP
Ilia_Sergeevich [38]

27) Partial pressure of oxygen: 57.8 kPa

29) Final volume: 80 mL

30) Final volume: 8987 L

31) Due to property of water of being polar, ice floats on water

Explanation:

27)

In a mixture of gases, the total pressure of the mixture is the sum of the partial pressures:

p_T = p_1 + p_2 + ... + p_N

In this problem, the mixture contains 3 gases (helium, carbon dioxide and oxygen). We know that the total pressure is

p_T=201.4 kPa

We also know the partial pressures of helium and carbon dioxide:

P_{He}=125.4 kPa\\P_{CO_2}=18.2 kPa

The total pressure can be written as

p_T=p_{He}+p_{CO_2}+p_{O_2}

where p_{O_2} is the partial pressure of oxygen. Therefore, we find

p_{O_2}=p_T-p_{He}-p_{CO_2}=201.4-125.4-18.2=57.8 kPa

29)

Assuming that the pressure of the gas is constant, we can apply Charle's law, which states that:

"For an ideal gas at constant pressure, the volume of the gas is proportional to its absolute temperature"

Mathematically,

\frac{V}{T}=const.

where

V is the volume of the gas

T is the Kelvin temperature

We can re-write it as

\frac{V_1}{T_1}=\frac{V_2}{T_2}

Here we have:

V_1 = 42 mL (initial volume)

T_1=-89^{\circ}C+273=184 K is the initial temperature

T_2=77^{\circ}C+273=350 K is the final temperature

Solving for V2, we find the final volume:

V_2=\frac{V_1 T_2}{T_1}=\frac{(42)(350)}{184}=80 mL

30)

For this problem, we can use the equation of state for ideal gases, which can be written as

\frac{p_1 V_1}{T_1}=\frac{p_2 V_2}{T_2}

where in this problem:

p_1 = 102.3 kPa is the initial pressure

V_1=1975 L is the initial volume

T_1=25^{\circ}C+273=298 K is the initial temperature

p_2=21.5 kPa is the final pressure

T_2=12^{\circ}C+273=285 K is the final temperature

And solving for V2, we find the final volume of the balloon:

V_2=\frac{p_1 V_1 T_2}{p_2 T_1}=\frac{(102.3)(1975)(285)}{(21.5)(298)}=8987 L

31)

A molecule of water consists of two atoms hydrogen bond with an atom of oxygen (H_2 O) in a covalent bond.

While the molecul of water is overall neutral, due to the higher electronegativity of the oxygen atom, electrons are slightly shifted towards the oxygen atom; as a result, there is a slightly positive charge on the hydrogen side, and a slightly negative charge on the oxygen side (so, the molecules is said to be polar).

As a consequence, molecules of water attract each other, forming the so-called "hydrogen bonds".

One direct consequence of the polarity of water is that ice floats on liquid water.

Normally, for every substance on Earth, the solid state is more dense than the liquid state. However, this is not true for water, because ice is less dense than liquid water.

This is due to the polarity of water. In fact, when the temperature of water is decreased to freezing point and water becomes ice, the hydrogen bondings "force" the molecules to arrange in a lattice structure, so that the molecules become more spaced when they turn into solid state. As a result, ice occupies more volume than water, and therefore it is less dense, being able to float on water.

Learn more about ideal gases:

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#LearnwithBrainly

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3 years ago
Question 43 please. i’m not sure if i got the right answer
hram777 [196]

a) The reaction is exothermic since the overall enthalpy change is negative. this means that the system has lost energy to the environment, namely, the apparatus and due to drought.

b) We first calculate the number of moles in 3.55 grams of magnesium.

number of moles= mass/ atomic mass

                            =3.55/24

                            =0.1479 moles(to 4sf)

now, if 2 moles of magnesium give -1204kJ

        How much energy is given by 0.1479 moles

       = (0.1479×-1204kJ)

        =-89.0358kJ (don't forget the negative sign)

c) two molesof MgO produces -1204kJ of energy

then -234kJ will be produced by

=(-234kJ×2moles)/1204kJ

=0.3887moles

one mole of MgO weighs 24+16=40

therefore the mass produced is 0.3887moles×40=15.548grams

(d) we first find the number of moles of MgO in 40.3 grams

number of moles=mass/RFM

=40.3g/40= 1.0075moles

if 2 moles of MgO give 1204 kJ then decomposing 1.0075 moles requires

(1.0075 moles×1204kJ)/2=606.515kJ

4 0
3 years ago
How many atoms are in a sample of chromium with a mass of 31 grams? O a 2.4 x 1024 atoms of chromium b 3.6 x 1023 atoms of chrom
lukranit [14]

Answer:

b. 3.66x10²³ atoms of chromium.

Explanation:

First we calculate how many moles are there in 31 grams of chromium, using its molar mass:

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Then we <u>calculate how many atoms are there in 0.608 moles</u>, using <em>Avogadro's number</em>:

  • 0.608 mol * 6.023x10²³ atoms/mol = 3.66x10²³ atoms

The correct answer is thus option b. 3.66x10²³ atoms of chromium.

4 0
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