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2 years ago

1. Imagine you have a sealed 20.0 L balloon filled with helium gas at 750 mmHg in the

Chemistry

1 answer:

SVETLANKA909090 [29]2 years ago

6 0

Answer:

17.6510 L

Explanation:

First we should get the number of moles of helium here by Boyle's law

PV=nRT

P=750/760= 0.9868 atm

T=25+273=298 kelvin

R= 0.08206

V= 20L

n=PV/RT

n=0.9868×20/0.08206×298

n=0.80707 mol

Then use the same law

V=0.80707×0.08206×263/0.9869=

17.6510L

SO THE VOLUME WILL BE 17.6510 L

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An elastic cord can be stretched to its elastic limit by a load of 2N.If a 35cm length of the cord is extended 0.6cm by a force

Levart [38]

Explanation:

$from \: hookes \: law \\ F = k.e \\ but \: e = 0.6 \: cm \\ 2 = k \times 0.6 \\ k = 3.33 \\ when \:F \: is \: 2.5 \\ 2.5 = 3.33 \times e {}^{.} \\ {e}^{. } = 0.75 \: cm \\ new \: length = 35 - {e}^{.} \\ = 35 - 0.75 \\ = 34.25 \: cm$

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2 years ago

The Ka for formic acid (HCO2H) is 1.8 × 10-4. What is the pH of a 0.35 M aqueous solution of sodium formate (NaHCO2)?

anzhelika [568]

Answer:

9.36

Explanation:

Sodium formate is the conjugate base of formic acid.

Also,

$K_a\times K_b=K_w$

$K_b$ for sodium formate is $K_b=\frac {K_w}{K_a}$

Given that:

$K_a$ of formic acid = $1.8\times 10^{-4}$

And, $K_w=10^{-14}$

So,

$K_b=\frac {10^{-14}}{1.8\times 10^{-4}}$

$K_b=5.5556\times 10^{-11}$

Concentration = 0.35 M

HCOONa ⇒ Na⁺ + HCOO⁻

Consider the ICE take for the formate ion as:

HCOO⁻ + H₂O ⇄ HCOOH + OH⁻

At t=0 0.35 - -

At t =equilibrium (0.35-x) x x

The expression for dissociation constant of sodium formate is:

$K_{b}=\frac {[OH^-][HCOOH]}{[HCOO^-]}$

$5.5556\times 10^{-11}=\frac {x^2}{0.35-x}$

Solving for x, we get:

x = 0.44×10⁻⁵ M

pOH = -log[OH⁻] = -log(0.44×10⁻⁵) = 4.64

pH + pOH = 14

So,

pH = 14 - 4.64 = 9.36

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3 years ago

A laboratory instructor gives a sample of amino acid powder to each of four students, i, ii, iii, and iv, and they weigh the sam

Elena L [17]

Let us differentiate accuracy from precision. Accuracy is the nearness of the measured value to the true or exact value. On the other hand, precision is the nearness of the measured values between each other. So, for precision, select the student in which the measured values are very near to each other. That would be Student III. Now, for accuracy, let's find the average for each student.

Student I: (8.72g+8.74g+8.70g)/3 = 8.72 g
Student II: (8.56g+8.77g+8.83g)/3 = 8.72 g
Student III: (8.50g+8.48g+8.51g)/3 = 8.50 g
Student IV: (8.41g+8.72g+8.55g)/3 = 8.56 g

From the given results, the accurate one would be Students I and II. So, we make a compromise. Even though Student III is precise, it is not accurate. If you compare between Students I and II, the more precise data would be Student I. Therefore, the answer is Student I.

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2 years ago

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The solubility of copper chloride at 20 °C is 73 g/100 g of water. Kiera adds 100 g of copper chloride to 100 g of water and sti

OLEGan [10]

Answer:

$m_{undissolved}=27g$

Explanation:

Hello there!

In this case, according to the given information of the solubility of copper chloride, as the maximum amount of this salt one can dissolve without having a precipitate, we infer that since just 73 grams are actually dissolved, the following amount will remain solid as a precipitate:

$m_{undissolved}=100g-73g\\\\m_{undissolved}=27g$

Best regards!

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2 years ago

Which of the following best explains what happens when you add ice to a glass of water?(2 points)

-Dominant- [34]

Answer:

Heat energy moves from the water to the ice cubes.

Explanation:

Heat energy moves from the water to the ice cubes, as water is at higher temperature than ice.

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2 years ago

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