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3 years ago

How will adding NaCl affect the freezing point of a solution?

Chemistry

2 answers:

lord [1]3 years ago

3 0

Answer is: adding NaCl will lower the freezing point of a solution.

A solution (in this example solution of sodium chloride) freezes at a lower temperature than does the pure solvent (deionized water).

The higher the solute concentration (sodium chloride), freezing point depression of the solution will be greater.

Equation describing the change in freezing point:

ΔT = Kf · b · i.

ΔT - temperature change from pure solvent to solution.

Kf - the molal freezing point depression constant.

b - molality (moles of solute per kilogram of solvent).

i - Van’t Hoff Factor.

Dissociation of sodium chloride in water: NaCl(aq) → Na⁺(aq) + Cl⁻(aq).

valentinak56 [21]3 years ago

3 0

Adding NaCl (salt) will lower the freezing point. Examples of this include salt water bodies like the ocean, and why salt is spread on roadways during snow and icy conditions.

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3 years ago

A 46.9 gram sample of a substance has a volume of about 3.5 centimeters3. It is solid at a room temperature of 23ºC. Out of the

horrorfan [7]

Answer : (C) Hafnium is the most likely identity of the given substance.

Solution : Given,

Mass of given substance (m) = 46.9 g

Volume of given substance (V) = 3.5 $Cm^{3}$

First, find the Density of given substance.

Formula used :

$Density=\frac{\text{Mass of given substance}}{\text{Voume of given substance}}$

Now,put all the values in this formula, we get

$Density=\frac{46.9 g}{3.5 Cm^{3} }$ = 13.4 g/ $Cm^{3}$

So, we conclude that the density of given substance (13.4 g/ $Cm^{3}$ ) is approximately equal to the density of Mercury and Hafnium (13.53 and 13.31 g/ $Cm^{3}$ respectively).

According to the question the substance is solid at room temperature but Mercury is liquid at room temperature. So, Mercury is not identical to the given substance.

Another element i.e, Hafnium is the element whose density is approximately equal to the given substance and also solid at room temperature. And we know that the melting point of solid is high.

So, Hafnium is the most likely element which is the identity of the given substance.

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3 years ago

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g Oxidation refers to ________ Select one: a. an increase in oxidation number. b. a decrease in oxidation number. c. an increase

mihalych1998 [28]

Answer:

The correct alternative is "Option a".

Explanation:

Oxidation has become a mechanism whereby the physicochemical properties transform attributed to the formation of O₂.

The connection involving magnesium as well as O₂ requires the oxidation of the component named magnesium.
Even before exposed to the air, silicon is oxidized as well as generates silicon dioxide.

Other possibilities are not connected to the scenario in question. So Choice A is the best option.

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2 years ago

Scientists take scientific measurements carefully in order to ensure their reliability and validity. Which of the following is a

Lemur [1.5K]

The correct answer is C. An example of measurement bias in scientific measurement, of the available answers, would be a balance that always reads 0.1g. The other possible answers are all examples of devices or measurement techniques that would help a scientist to avoid measurement bias, rather than contributing to it.

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3 years ago

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Write the formula for potassium oxide. why do you not need prefixes in the name

Molodets [167]

Potassium oxide: K₂O.

There's no need for prefixes since K₂O is an ionic compound.

<h3>Explanation</h3>

Find the two elements on a periodic table:

Potassium- K- on the left end of period four.
Oxygen- O- near the right end of periodic two.

Elements on the bottom-left corner of the periodic table are metals. Those on the top-right corner are nonmetals.

Potassium is a metal,
Oxygen is a nonmetal.

A metal and a nonmetal combine to form an ionic compound. Potassium oxide is likely to be an ionic compound. It contains two types of ions:

Potassium ions: Potassium is group 1 of the periodic table. It is an alkaline metal. Like other alkaline metals such as sodium Na, potassium K tends to lose one electron and form ions of charge +1 in compounds. The ion would be K⁺.

Oxide ions from oxygen: Oxygen is the second most electronegative element on the periodic table. It tends to gain two electrons and form the oxide ion $\text{O}^{2-}$ when it combines with metals.

The two types of ions carry opposite charges. They shall pair up at a certain ratio such that they balance the charge on each other. The charge on each $\text{O}^{2-}$ ion is twice that on a $\text{K}^{+}$ ion. Each $\text{K}^{+}$ would pair up with two $\text{O}^{2-}$ . Hence the subscript in the formula: $\text{K}_{\bf 2}\text{O}$ .

There are two classes of compounds:

Covalent compounds, which need prefixes, and
Ionic compounds, which need no prefix.

Prefixes are needed only in covalent compounds. For instance in the covalent compound carbon dioxide $\text{CO}_2$ , the prefix di- indicates that there are two oxygen atoms in the formula $\text{CO}_2$ . However, there's no need for prefix in ionic compounds such as $\text{K}_2\text{O}$ .

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