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4 years ago

Calculate the freezing point (Kf = 1.86 °C/m) of a 2.1m aqueous solution of KCl.

Chemistry

1 answer:

Wittaler [7]4 years ago

7 0

Answer:

The freezing point of the solution is - 3.90 °C.

Explanation:

We can solve this problem using the relation:

where, ΔTf is the depression in the freezing point.

Kf is the molal freezing point depression constant of water = - 1.86 °C/m,

m is the molality of the solution (m = 2.1 m).

<em>∴ ΔTf = (Kf)(m)</em> = (-1.86 °C/m)(2.1 m) =<em> - 3.90 °C.</em>

<em>∵ The freezing point if water is 0.0 °C and it is depressed by - 3.90 °C.</em>

<em>∴ The freezing point of the solution is - 3.90 °C.</em>

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Using only the periodic table, determine the element that displays each given trend. Be sure to provide your reasoning.

RideAnS [48]

Choose the element that:

- is more reactive: oxygen or argon.

- has the larger atomic radius: francium or sodium.

- has the smaller atomic radius: scandium or selenium.

- has more ionization energy: bismuth or mercury.

- has less ionization energy: nitrogen or phosphorus.

- has more electronegativity: xenon or silver.

- has less electronegativity: titanium or hafnium.

Explanation:

Choose the element that is more reactive: oxygen or argon.

Argon have a complete electronic shell which makes him inert from chemically point of view while oxygen is able to form compounds with the majority of the elements.

Choose the element that has the larger atomic radius: francium or sodium.

As you go down in a group the atomic radius is increasing.

Choose the element that has the smaller atomic radius: scandium or selenium.

As a general trend the atomic radius of elements decrease in periods from right to left for this elements .

Choose the element that has more ionization energy: bismuth or mercury.

Mercury have a complete electronic shell (5d¹⁰) while bismuth have 3 electrons in the last shell (6p³). It is harder to extract an electron from mercury compared to bismuth.

Choose the element that has less ionization energy: nitrogen or phosphorus.

Ionization energy decrease as you go down in a group.

Choose the element that has more electronegativity: xenon or silver.

Silver have a higher electronegativity than Xenon. Xenon is an inert gas and it has a complete electronic shell which explains his inert chemical reactivity.

Choose the element that has less electronegativity: titanium or hafnium.

As you go down a grup electronegativity is decreasing.

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trends in periodic table:

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3 years ago

Which statement is most consistent with the plum pudding model of the atom?

lianna [129]

The answer to this question would be: <span>1) Electrons occupy regions of space
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In plum pudding model, the atoms are drawn as pudding and the negative particle is spread around the pudding. In this model, the electron is spread but not moving in orbit. Rutherford model that comes afterward is the one that says most of the atoms is empty space.</span>

3 0

3 years ago

Read 2 more answers

How many molecules of ammonia are produced from the reaction of

vivado [14]

Answer:

9.5X10^23 molecules N2 X (2 molecules NH3 / 1 molecule N2) = 1.9X10^24 molecules NH3

Explanation:

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3 years ago

A substance decays so that the amount a of the substance left at time t is given by: a = a0 ∙ (0.8)t where a0 is the original am

Zolol [24]

The half-life of the substance is 3.106 years.

<h3>What is the formula for exponential decay?</h3>

The exponential decline, which is a rapid reduction over time, can be calculated with the use of the exponential decay formula.
The exponential decay formula is used to determine population decay, half-life, radioactivity decay, and other phenomena.
The general form is F(x) = a.

Here,

a = the initial amount of substance

1-r is the decay rate

x = time span

The equation is given in its correct form as follows:

a = $a_{0}$ × $(0.8)^{t}$

As this is an exponential decay of a first order reaction, t is an exponent of 0.8.

Now let's figure out the half life. Since the amount left is half of the initial amount at time t, that is when:

a = 0.5 a0

<h3>Substituting this into the equation:</h3>

0.5 $a_{0}$ = $a_{0}$ × $(0.8)^{t}$

0.5 = $(0.8)^{t}$

taking log on both sides

t log 0.8 = log 0.5

t = log 0.5/log 0.8

t = 3.106 years

The half-life of the substance is 3.106 years.

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1 year ago

Which variable is tested during a lab investigation

Licemer1 [7]

Actually, it could indeed be the independent variable.

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3 years ago