CHEMISTRY HIGH SCHOOL

What is the melting point of a 3L aqueous solution that contains 100g of MgCl2? kf H2O=1.86 rhoH2O=1gmL

Answers

Answer 1

Answer:

Answer:

Melting point of aqueous solution = -10.32 °C

Explanation:

$\Delta T_f=i * k_f * m$

Where,

ΔT_f = Depression in freezing point

k_f = molal depression constant

m = molality

Formula for the calculation of molality is as follows:

$m=(Mass\ of\ solute\ (kg))/(molecular\ mass\ of\ solute * mass\ of\ solvent)$

density of water = 1 g/mL

density = mass/volume

Therefore,

mass = density × volume

volume = 3 L = 3000 mL

Mass of water = 1 g/mL × 3000 mL

= 3000 g

$Molality(m)=(100*1000)/(18* 3000) \n=1.85\ m$

van't Hoff factor (i) for MgCl2 = 3

Substitute the values in the equation (1) to calculate depression in freezing point as follows:

$\Delta T_f=i * k_f * m\n=3* 1.86 * 1.85\n=10.32\ °C$

Melting point of aqueous solution = 0 °C - 10.32 °C

= -10.32 °C

Answer 2

Answer:

Answer:

The melting point of the solution is - 1.953 °C

Explanation:

In an ideal solution, the freezing point depression is computed as follows:

$ΔT_f = k_f * b * i$

where:

$ΔT_f$ is the freezing-point depression

$k_f$ is the cryoscopic constant, in this case is equal to 1.86

b is the molality of the solution

i is the van't Hoff factor, number of ion particles per individual molecule of solute, in this case is equal to 3

Molality is defined as follows:

b = moles of solute/kg of solvent

Moles of solute is calculated as follows:

moles of solute = mass of solute/molecular weight of solute

In this case there are 100 g of solute and its molecular weight is 35.5*2 + 24 = 95 g/mole. So, the moles are:

moles of solute = 100 g/(95 g/mol) = 1.05 moles

The mass of solvent is computed as follows:

mass of solvent = density of solvent * Volume of solvent

Replacing with the data of the problem we get:

mass of solvent = 1 kg/L*3 L = 3 kg

Finally, the molality of the solution is:

b = 1.05/3 = 0.35 mol/kg

Then, the freezing-point depression is:

$ΔT_f = 1.86 * 0.35 * 3$

$ΔT_f = 1.953 C$

The freezing-point depression is the difference between the melting point of the pure solvent (here water) and the melting point of the solution. We know that the the melting point of water is 0 °C, then:

melting point of water - melting point of the solution = 1.953 °C

melting point of the solution = 0 °C - 1.953 °C = - 1.953 °C

Related Questions

Which of these best describes the difference between the formulas for nitrogen monoxide and nitrogen dioxide? Which of these best describes the difference between the formulas for nitrogen monoxide and nitrogen dioxide? F. Nitrogen monoxide has one more atom of nitrogen. G. Nitrogen dioxide has one fewer atom of oxygen H. Nitrogen monoxide has one fewer atom of oxygen J. Nitrogen dioxide has one more atom of nitrogen show more Which of these best describes the difference between the formulas for nitrogen monoxide and nitrogen dioxide? F. Nitrogen monoxide has one more atom of nitrogen. G. Nitrogen dioxide has one fewer atom of oxygen H. Nitrogen monoxide has one fewer atom of oxygen J. Nitrogen dioxide has one more atom of nitrogen
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When dilute sulphuric acid is added to barium chloride solution then what happens in a balanced equation?

What is the name of the compound with the chemical formula (NH4)2S?A. ammonium sulfide
B. hydrogen sulfate
C. sulfur hydride
D. sulfuric acid

Answers

NH₄⁺ - ammonium cation
S²⁻ - sulfide anion

(NH₄)₂S - ammonium sulfide
The answer is A.

Final answer:

The compound with the chemical formula (NH4)2S is ammonium sulfide. This name signifies the presence of two ammonium ions and a single sulfide ion in the compound.

Explanation:

The compound with the chemical formula (NH4)2S is ammonium sulfide. In this compound, there are two ammonium ions (NH4) for every sulfide ion (S2-). The positive charge of the two ammonium ions balances the negative charge of the sulfide ion, forming a neutral compound. The prefixes and suffixes in the name of the compound indicate the elements present and their ratios.

Learn more about Ammonium Sulfide here:

brainly.com/question/5523357

#SPJ6

The rare earth elements include

Answers

The rare earth elements include the lanthanide series, scandium and yttrium. They are a set of seventeen chemical elements in the periodic table. They really are not that rare but they occur together in nature and are hard to separate from one another.

Answer:

I tried the lanthanide series and the alkali metals and it was wrong, I think the only other option would be the lanthanide series and the actinide series.

Sorry!!!

The mass of a nitrogen atom is 14 u. What is the mass, in grams, of 2 mol of N ?

Answers

Answer:

28 grams

Explanation:

Molar mass of Nitrogen = 14 u

Mass = Mole * Molar Mass

= 2 * 14

= 28 g

In which reaction are electrons transferred from one reactant to another reactant?(1) 2Ca(s) + O2(g) =>2CaO(s)
(2) AgNO3(aq) + KCl(aq) =>AgCl(s) + KNO3(aq)
(3) HCl(aq) + NaOH(aq) =>NaCl(aq) + H2O(l)
(4) H3O+(aq) + OH-(aq) => 2H=O(l)

Answers

Answer : The correct reaction is, (1) $2Ca(s)+O_2(g)\rightarrow 2CaO(s)$

Explanation :

(1) $2Ca(s)+O_2(g)\rightarrow 2CaO(s)$

In this reaction, the oxidation state of calcium (Ca) changes from (0) to (+2) and the oxidation state of oxygen (O) changes from (0) to (-2). In this reaction the electrons are transferred from one reactant (calcium) to another reactant (oxygen). This is a synthesis reaction.

(2) $AgNO_3(aq)+KCl(aq)\rightarrow AgCl(s)+KNO_3(aq)$

In this reaction, there is no changes in the oxidation state of the elements. So, in this reaction, no electrons transferred from one reactant to another reactant. This is a double-displacement reaction.

(3) $HCl(aq)+NaOH(aq)\rightarrow NaCl(aq)+H_2O(l)$

In this reaction, there is no changes in the oxidation state of the elements. So, in this reaction, no electrons transferred from one reactant to another reactant. This is a neutralization reaction.

(4) $H_3O^+(aq)+OH^-(aq)\rightarrow 2H_2O(l)$

In this reaction, there is no changes in the oxidation state of the elements. So, in this reaction, no electrons transferred from one reactant to another reactant. This is a combination reaction.

Hence, the correct reaction is, (1) $2Ca(s)+O_2(g)\rightarrow 2CaO(s)$ in which the electrons transferred from one reactant to another reactant.

The answer is (1). The electrons transfer form one reactant to another means that there is the change of valence. For other choices, the valence of reactant does not change.

The process of splitting an atom into two lighter atoms is called A. nuclear disintegration.
B. nuclear separation.
C. nuclear fission.
D. nuclear fusion.

Answers

Answer is: C. nuclear fission.

Nuclear fission is a nuclear reaction or a radioactive decay where nucleus of atom split into smaller ligher nuclei.

Nuclear fission is exothermic reaction which release large amounts of energy (electromagnetic radiation or as kinetic energy, which heat reactors where fission reaction take place).

Answer: The process of splitting of an atom into two lighter atoms is called is called nuclear fission.

Explanation:

There are two types of nuclear decay reactions:

Nuclear fission reactions: They are defined as the reaction in which, the heavier atoms splits into two or more lighter atoms. The number of atoms formed in this reaction increases from the given atoms.
Nuclear fusion reactions: They are defined as the reaction in which, two or more lighter atoms combine to form a heavier atom. The number of atoms formed in this reaction decreases from the given atoms.

Hence, the process of splitting of an atom into two lighter atoms is called is called nuclear fission.

What can be concluded if an ion of an element is smaller than an atom of the same element?(1) The ion is negatively charged because it has fewer electrons than the atom.
(2) The ion is negatively charged because it has more electrons than the atom.
(3) The ion is positively charged because it has fewer electrons than the atom.
(4) The ion is positively charged because it has more electrons than the atom.

Answers

The question is,'what can be concluded if the ion of an element is smaller than the atom of the same element'. The correct option is 'the ion is positively charged because it has fewer electrons than the atom. An atom becomes charged either by donation or accepting electrons. When an atom donate electrons, it becomes positively charged and it has less electrons than its atom. For instance, calcium has 20 electrons, it becomes an ion by donating its two electrovalent electrons, thereby having only 18 electrons left. But when an element accepts electrons, it becomes negatively charged and has more electrons than its atom.

The following conclusion can be made if an ion of an element is smaller than an atom of the same element:

$\boxed{\left( 3 \right){\text{ The ion is positively charged because it has fewer electrons than the atom}}{\text{.}}}$

Further explanation:

Ions are the entities with a net electric charge, be it positive or negative. Since positive and negative charges can be present on the ions, ions are of two types-positively charged and negatively charged ions. The ions formed by loss of electrons develop a positive charge and are called cations. But the ions produced by the gain of electrons acquire a negative charge and are called anions.

Since cations are positively charged ions, these have fewer electrons as compared to the corresponding neutral atom. So these ions experience stronger forces of attraction with the atomic nucleus and are smaller in size in size than the parent atom.

Anions are formed by the addition of electrons to the neutral atom. It has more electrons than the parent atom so it feels electron-electron repulsion due to which its size becomes larger than the parent atom.

So cations are smaller than the parent atom of the same element whereas anions are larger than the parent atoms. Therefore if an ion is smaller than the atom, it is positively charged due to the presence of fewer electrons than the parent atom.

Learn more:

Component of John Dalton’s atomic theory: brainly.com/question/2357175
Basis of investigation for the scientists: brainly.com/question/158048

Answer details:

Grade: Senior School

Chapter: Atomic structure

Subject: Chemistry

Keywords: ions, cations, anions, loss, gain, electrons, net electric charge, electron-electron repulsion, parent atom, smaller, larger, size, neutral atom, positive charge, negative charge.

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