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3 years ago

5

What can you predict about the properties of xenon and helium, both in group 18 in the periodic table? why?

1 answer:

elixir [45]3 years ago

4 0

They are very stable. they have a "full table" so to speak. they have no valance electrons. they do not give electrons and they do not take them either. there are very few if an elements that can be paired with noble gasses

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For a process Arightwards harpoon over leftwards harpoonB, at 25 °C there is 10% of A at equilibrium while at 75 °C, there is 80

Lostsunrise [7]

This question is describing the following chemical reaction at equilibrium:

$A\rightleftharpoons B$

And provides the relative amounts of both A and B at 25 °C and 75 °C, this means the equilibrium expressions and equilibrium constants can be written as:

$K_1=\frac{90\%}{10\%}=9\\\\K_2=\frac{20\%}{80\%} =0.25$

Thus, by recalling the Van't Hoff's equation, we can write:

$ln(K_2/K_1)=-\frac{\Delta H}{R}(\frac{1}{T_2} -\frac{1}{T_1} )$

Hence, we solve for the enthalpy change as follows:

$\Delta H=\frac{-R*ln(K_2/K_1)}{(\frac{1}{T_2} -\frac{1}{T_1} ) }$

Finally, we plug in the numbers to obtain:

$\Delta H=\frac{-8.314\frac{J}{mol*K} *ln(0.25/9)}{[\frac{1}{(75+273.15)K} -\frac{1}{(25+273.15)K} ] } \\\\\\\Delta H=4,785.1\frac{J}{mol}$

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5 0

2 years ago

What happens when water is added to quicklime? Write two observations.

Neporo4naja [7]

Answer:

1.Most metal oxides are insoluble in water but some of these (e.g. Na2O.

Explanation:

2.: (i) A hissing sound is observed.

1.ii) The mixture starts boiling and lime water is obtained.

3 0

2 years ago

What is the valence of K2O2

raketka [301]

14 since K has 1 valence but there’s two so 2 valence for k and oxygen has 6 but there’s two so 12

6 0

3 years ago

Which of the following statements describes the correct method of preparation of 1.00 L of a 2.0 M urea solution?

Zolol [24]

Answer:

To prepare 1.00 L of 2.0 M urea solution, we need to dissolve 120 g of urea in enough water to produce a total of 1.00 L solution

Explanation:

Molarity of a solute in a solution denotes number of moles of solute dissolved in 1 L of solution.

So, moles of urea in 1.00 L of a 2.0 M urea solution = 2 moles

We know, number of moles of a compound is the ratio of mass to molar mass of that compound.

So, mass of 2 moles of urea = $(2\times 60.06)g=120 g$

Therefore to prepare 1.00 L of 2.0 M urea solution, we need to dissolve 120 g of urea in enough water to produce a total of 1.00 L solution

So, option (C) is correct.

8 0

3 years ago

Protactinium has 516 years of half life how many decays will it go through to become 1/64th of the substance? ,

Ulleksa [173]

Answer:

6 decays

Explanation:

Each half life period reduced the amount of substance by half

64 = 2⁶
1/64 = (1/2)⁶

So 6 of half life cycles or decays will go.

6 0

3 years ago