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3 years ago

Explain how melting points are used to identify compounds and determine purity. g\

Chemistry

1 answer:

Oduvanchick [21]3 years ago

4 0

Answer: melting points are major means of identifying pure compounds.

Explanation:

A pure compound can be identified by its melting point because, a pure compound will have a sharp melting point while an impure compound will melt over a temperature range. If presented with a pure sample of an unknown solid, its melting point can tell us what the identity of the compound. Similarly, melting point analysis can show the purity of a known solid. If the known solid has a sharp melting point, then it is pure.

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3 years ago

Uranium is a metallic element that is used in nuclear reactors and nuclear weapons. the vast majority of uranium found on earth

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4 years ago

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2 years ago

A mixture contains 21.7 g NaCl,

dolphi86 [110]

Answer:

$n_{tot}=0.652mol$

Explanation:

Hello there!

In this case, according to the given problem, it is possible to use the given molar masses of NaCl, KCl and LiCl in order to calculate the total moles, yet we calculate the moles of each salt first as shown below:

$n_{NaCl}=21.7gNaCl*\frac{1molNaCl}{58.44gNaCl}=0.371molNaCl\\\\ n_{KCl}=3.74gKCl*\frac{1molKCl}{74.55KCl}=0.0502molNaCl\\\\ n_{LiCl}=9.76gLiCl*\frac{1molLiCl}{42.39gLiCl}=0.230molLiCl$

Then, we add them all together to obtain:

$n_{tot}=0.371mol+0.0502mol+0.230mol\\\\n_{tot}=0.652mol$

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7 0

3 years ago

Calculate the pressure in atm of .68 mol of H at 298K and occupying 4.5 L

inessss [21]

Answer:

3.7 atm

General Formulas and Concepts:

Atomic Structure

Moles

Gas Laws

Ideal Gas Law: PV = nRT

P is pressure
V is volume
n is number of moles
R is gas constant
T is temperature

Explanation:

Step 1: Define

Identify variables

[Given] n = 0.68 mol H

[Given] T = 298 K

[Given] V = 4.5 L

[Given] R = 0.0821 L · atm · mol⁻¹ · K⁻¹

[Solve] P

Step 2: Find Pressure

Substitute in variables [Ideal Gas Law]: P(4.5 L) = (0.68 mol)(0.0821 L · atm · mol⁻¹ · K⁻¹)(298 K)
Multiply [Cancel out units]: P(4.5 L) = (0.055828 L · atm · K⁻¹)(298 K)
Multiply [Cancel out units]: P(4.5 L) = 16.6367 L · atm
Isolate P [Cancel out units]: P = 3.69705 atm

Step 3: Check

Follow sig fig rules and round. We are given 2 sig figs as our lowest.

3.69705 atm ≈ 3.7 atm

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3 years ago