Group 1A elements (except for hydrogen) are known as the alkali metals. a. True b. False

1 answer:

5 0

The answer is true that Group 1A elements (except for hydrogen) are the alkali metals. Groups 2A are alkaline earth metals. Group 3B-12B are transition metals. Group 3A to 4A except Boron, Carbon, Nitrogen, oxygen, silicon, phosphorus, sulfur, germanium, astatine, selenium, antimony, tellurium, polonium are basic metal. Carbon, nitrogen, oxygen, phosphorus, sulfur and selenium are nonmetals. Boron, silicon, germanium, astatine, antimony, tellurium and polonium are metalloids. Groups 7A are halogens. Groups 8A are noble gases. The lower part of the periodic table are lanthanides and actinides.

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A solution is prepared by dissolving 27.0 g of urea [(NH2)2CO], in 150.0 g of water. Calculate the boiling point of the solution

andrew11 [14]

Answer: The boiling point of solution is 101.56°C

Explanation:

Elevation in boiling point is defined as the difference in the boiling point of solution and boiling point of pure solution.

The equation used to calculate elevation in boiling point follows:

$\Delta T_b=\text{Boiling point of solution}-\text{Boiling point of pure solution}$

To calculate the elevation in boiling point, we use the equation:

$\Delta T_b=iK_bm$

Or,

$\text{Boiling point of solution}-\text{Boiling point of pure solution}=i\times K_b\times \frac{m_{solute}\times 1000}{M_{solute}\times W_{solvent}\text{ (in grams)}}$

where,

Boiling point of pure water = 100°C

i = Vant hoff factor = 1 (For non-electrolytes)

$K_b$ = molal boiling point elevation constant = 0.52°C/m.g

$m_{solute}$ = Given mass of solute (urea) = 27.0 g

$M_{solute}$ = Molar mass of solute (urea) = 60 g/mol

$W_{solvent}$ = Mass of solvent (water) = 150.0 g

Putting values in above equation, we get:

$\text{Boiling point of solution}-100=1\times 0.52^oC/m\times \frac{27\times 1000}{60\times 150}\\\\\text{Boiling point of solution}=101.56^oC$

Hence, the boiling point of solution is 101.56°C

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4 years ago

Place these hydrocarbons in order of decreasing boiling point. Rank from highest to lowest boiling point. 1. Paraffin, C40Hg2 2.

lesya [120]

Answer:

Paraffin > Heptadecane > Hexane > 2,2-dimethylbutane > Propane

Explanation:

It must first be establish that all the molecules listed in the question are alkanes. For alkanes, the intermolecular forces between the molecules of alkanes increases with increasing molecular weight. This is as a result of increase in the surface area of the molecule. Increase in surface area implies a greater degree of dispersion forces.

This is the reason why high boiling points are observed for high molecular weight alkanes.

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3 years ago

What’s the density of a polypropylene

maria [59]

Answer:

0.92 g/cm³

hope this helps

3 0

3 years ago

PLZ HURRY!

cestrela7 [59]