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3 years ago

What is the molality of a solution made by dissolving 137.9g of sucrose in 414.1g of water?

Chemistry

1 answer:

Daniel [21]3 years ago

8 0

Answer: 2.71 moles of solute for every 1 kg of solvent.

Explanation: As you know, the molality of a solution tells you the number of moles of solute present for every 1 kg of the solvent.This means that the first thing that you need to do here is to figure out how many grams of water are present in your sample. To do that, use the density of water.500.mL⋅1.00 g1mL=500. g Next, use the molar mass of the solute to determine how many moles are present in the sample.115g⋅1 mole NanO385.0g=1.353 moles NaNO3So, you know that this solution will contain 1.353moles of sodium nitrate, the solute, for 500. g of water, the solvent.In order to find the molality of the solution, you must figure out how many moles of solute would be present for 1 kg=103g of water.103g water⋅1.353 moles NaNO3500.g water=2.706 moles NaNO3You can thus say that the molality of the solution is equal to molality=2.706 mol kg−1≈2.71 mol kg−1 The answer is rounded to three sig figs.

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Which pair has identical electron configurations?

Thepotemich [5.8K]

Identical electron configurations : K⁺ and Cl⁻

<h3>Further explanation </h3>

In an atom, there are levels of energy in the shell and sub-shell

This energy level is expressed in the form of electron configurations.

Charging electrons in the sub-shell uses the following sequence:

S²⁻ and CI

S²⁻ : [Ne] 3s²3p⁶

Cl : [Ne] 3s²3p⁵

K⁺ and CI⁻

K⁺ : 1s² 2s² 2p⁶ 3s² 3p⁶

Cl⁻ : 1s² 2s² 2p⁶ 3s²3p⁶

S and Ar

S :[Ne] 3s²3p⁴

Ar : [Ne] 3s²3p⁶

Cl⁻ and K

Cl⁻ : 1s² 2s² 2p⁶ 3s²3p⁶

K : 1s² 2s² 2p⁶ 3s² 3p⁶4s¹

6 0

3 years ago

Are the following statements true or false? (a) Formal charges represent an actual separation of charges. true false (b) ΔH o rx

katrin [286]

Answer:

Explanation:

A) Formal charges represent an actual separation of charges.(FALSE)

(B) ΔHo rxn can be estimated from the bond enthalpies of reactants and products.(TRUE)

C)All second-period elements obey the octet rule in their compounds(FALSE).

(D)The resonance structures of a molecule can be separated from one another in the laboratory.(FALSE)

Bond enthalpy which is also reffered to as bond energy is the amount of energy that is required to break one mole of a bond.

taking the single bond between Oxygen and Hydrogen into considerationthe bond energy between their single bond is 463 kJ/mol.

formal charge is used for the comparison of the number of electrons present around an atom in a particular molecule with the number of electrons present around a neutral

3 0

3 years ago

10.

Andru [333]

Answer: 1.8 moles Fe and 2.7 moles $CO_2$ are produced.

Explanation:

The balanced chemical reaction is:

$Fe_2O_3+3CO\rightarrow 2Fe+3CO_2$

According to stoichiometry :

3 moles of $CO$ require 1 mole of $Fe_2O_3$

Thus 2.7 moles of $CO$ will require= $\frac{1}{3}\times 2.7=0.9moles$ of $Fe_2O_3$

Thus $CO$ is the limiting reagent as it limits the formation of product and $Fe_2O_3$ is the excess reagent.

As 3 moles of $CO$ give = 2 moles of $Fe$ and 3 moles of $CO_2$

Thus 2.7 moles of $CO$ will give = $\frac{2}{3}\times 2.7=1.8moles$ of $Fe$ and $\frac{3}{3}\times 2.7=2.7moles$ of $CO_2$

Thus 1.8 moles Fe and 2.7 moles $CO_2$ are produced.

7 0

3 years ago

When might neutralization reactions be used in a laboratory setting?

Ipatiy [6.2K]

Neutralization reactions can be used in a laboratory setting in order t<span>o dispose of chemicals. When spills happens, for instance an acid is on the floor, you can use a base to neutralize the spill. Hope this answers the question. Have a nice day.</span>

6 0

3 years ago

A gas with a volume of 250 mL at a temperature of 293K is heated to 324K. What is the new volume of the gas?

ANEK [815]

Answer:

The new volume of the gas is 276.45 mL.

Explanation:

8 0

3 years ago