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2 years ago

A solution is prepare using 45.2 g of an unknown (nonelectrolyte) dissolved in 476.4 g of water. The freezing point depression

Chemistry

1 answer:

Ray Of Light [21]2 years ago

6 0

Answer:

94.4g/mol is molar mass of the unknown

Explanation:

Based on the freezing point depression equation:

ΔT = Kf*m*i

<em>Where ΔT is the depression in freezing point (1.87°C)</em>

<em>Kf is freezing point depression constant of water (1.86°Ckg/mol)</em>

<em>And i is Van't Hoff factor (1 for nonelectrolyte solutes)</em>

<em />

Replacing:

1.87°C = 1.86°CKg/mol*m*i

1.005mol/kg solvent = m

Using the mass of the solvent we can find the oles of the nonelectrolyte:

1.005mol/kg solvent * 0.4764kg = 0.479moles

Molar mass is defined as the ratio between mass of a substance in grams and moles, that is:

45.2g / 0.479mol =

<h3>94.4g/mol is molar mass of the unknown</h3>

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How many hydrogen's are in 6HCI

wolverine [178]

Answer:

6 atoms

Explanation:

In 6 moles of HCL (hydrochloric acid), there are 6 hydrogen atoms. Think about it this way: there is one hydrogen atom in HCL, or one hydrogen atom in one mole of HCL. Since there are 6 moles of HCL instead of one, this means there are six times as many hydrogen atoms. 6 times 1 is 6.

4 0

3 years ago

What is the chemical name for the balanced equation? 2Al+3Pb(NO3)2=2Al(NO3)3+3Pb

Zigmanuir [339]

The chemical name for reactant side:

Al - Aluminium, Pb(NO3)2 - Lead(II) nitrate.

The chemical name for product side:

Al(NO3)3 - Aluminium nitrate, Pb - lead.

<u>Explanation</u>:

This is an oxidation-reduction (redox) reaction:

3 $Pb^{II}$ + 6 e- → 3 $Pb^{o}$ (reduction)

2 $Al^{o}$ - 6 e- → 2 $Al^{III}$ (oxidation)

Pb(NO3)2 is an oxidizing agent, Al is a reducing agent.

Reactants:

Al uminium

Names: Aluminum, Aluminium powder, Al

Appearance: Silvery-white-to-grey powder, Silvery-white,

malleable, ductile, odorless metal.

Pb(NO3)2 – Lead(II) nitrate

Other names: Lead nitrate, Plumbous nitrate, Lead dinitrate

Appearance: White colorless crystals, White or colorless crystals

Products:

Al(NO3)3 – Aluminium nitrate

Other names: Nitric Aluminum salt, Aluminum nitrate,

Aluminium(III) nitrate

Appearance: White crystals, solid | hygroscopic

Pb - lead

Names: Lead, Lead metal, Plumbum

Appearance: Bluish-white or silvery-grey solid in various forms.

Turns tarnished on exposure to air. A heavy, ductile,

soft, gray solid.

8 0

3 years ago

SOMEONE PLEASE HELP

Zinaida [17]

Answer:

6. 7870 kg/m³ (3 s.f.)

7. 33.4 g (3 s.f.)

8. 12600 kg/m³ (3 s.f.)

Explanation:

6. The SI unit for density is kg/m³. Thus convert the mass to Kg and volume to m³ first.

1 kg= 1000g

1m³= 1 ×10⁶ cm³

Mass of iron bar

= 64.2g

= 64.2 ÷1000 kg

= 0.0642 kg

Volume of iron bar

= 8.16 cm³

= 8.16 ÷ 10⁶

$= 8.16 \times 10^{ - 6} \: kg$

$\boxed{density = \frac{mass}{volume} }$

Density of iron bar

$= \frac{0.0642}{8.16 \times 10^{ - 6} }$

= 7870 kg/m³ (3 s.f.)

$\boxed{mass = density \: \times volume}$

Mass

= 1.16 ×28.8

= 33.408 g

= 33.4 g (3 s.f.)

8. Volume of brick

= 12 cm³

$= 12 \times 10^{ - 6} \: m^{3} \\ = 1.2 \times 10^{ - 5} \: m ^{3}$

Mass of brick

= 151 g

= 151 ÷ 1000 kg

= 0.151 kg

Density of brick

= mass ÷ volume

$= \frac{0.151} {1.25 \times 10^{ - 5} } \\ = 12600 \: kg/ {m}^{3}$

(3 s.f.)

6 0

3 years ago

(HELP ME ASAP!)

slega [8]

A) Ca(OH)2 + CO2 —> CaCO3 + H2O

B) when Ca(OH)2 is reacted with CO2, the CaCO3 produced is a precipitate which turns the solution milky

8 0

3 years ago

Methane burns in the presence of oxygen to form carbon dioxide and water.

wlad13 [49]

Answer:

= 9.28 g CO₂

Explanation:

First write a balanced equation:

CH₄ + 2O₂ -> 2H₂O + CO₂

Convert the information to moles

7.50g CH₄ = 0.46875 mol CH₄

13.5g O₂ = 0.421875 mol O₂

Theoretical molar ratio CH₄:O₂ -> 1:2

Actual ratio is 0.46875 : 0.421875 ≈ 1:1

If all CH₄ is used up, there would need to be more O₂

So O₂ is the limiting reactant and we use this in our equation

Use molar ratio to find moles of CO₂

0.421875 mol O₂ * 1 mol CO₂/2 mol O₂=0.2109375 mol CO₂

Then convert to grams

0.2109375 mol CO₂ = 9.28114 g CO₂

round to 3 sig figs

= 9.28 g CO₂

5 0

3 years ago