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2 years ago

Compare the properties of elements in groups 17 and group 18. Make sure to cover the following points:

Chemistry

2 answers:

My name is Ann [436]2 years ago

7 0

The answer for this question is b

murzikaleks [220]2 years ago

5 0

Answer:

The answer.

Explanation:

Group 17 consists of Halogens, and group 18 consists of Noble Gases.

Group 17 are very high electronegativities. They have seven valence electrons. They are highly reactive, especially with alkali metals and alkaline earth.

In group 18 their elements are the most stable due to having the maximum number of valence electrons their outer shell can hold. Therefore, they rarely react with other elements since they are already stable.

Nobel gases are placed there because they are extremely unreactive.

Halogen elements are placed there because they have seven valence electrons, they only require one additional electron to form a full octet.

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Solid sodium reacts violently with water, producing heat, hydrogen gas, and sodium hydroxide. How many molecules of hydrogen gas

Zinaida [17]

Answer: Number of molecules of hydrogen gas $6.32\times 10^{32}$

Explanation:

$2Na+2H_2O\rightarrow 2NaOH+H_2$

Number of moles of sodium = $\frac{\text{mass of sodium}}{\text{molar mass of sodium}}=\frac{48.7 g}{23 g/mol}=2.11mol$

According to reaction , 2 moles of sodium produces 1 mole of hydrogen gas , then 2.11 mol of sodium will= $\frac{1}{2}\times 2.11 mol$ of hydrogen gas that is 1.05 moles of hydrogen gas.

Number of molecules = $N_A(\text{Avogadro number})\times$ moles of substance

Moles of hydrogen gas formed = 1.05 moles

Number of molecules of hydrogen gas = $N_A\times$ moles of hydrogen gas

Number of molecules of hydrogen gas $=6.022\times 10^{23} mole^{-1}\times 1.05 mole=6.32\times 10^{32}$

8 0

3 years ago

Butane (C4 H10(g), Hf = –125.6 kJ/mol) reacts with oxygen to produce carbon dioxide (CO2 , Hf = –393.5 kJ/mol ) and water (H2 O,

WITCHER [35]

Answer: Enthalpy of combustion (per mole) of $C_4H_{10} (g)$ is -2657.5 kJ

Explanation:

The chemical equation for the combustion of butane follows:

$2C_4H_{10}(g)+4O_2(g)\rightarrow 8CO_2(g)+10H_2O(g)$

The equation for the enthalpy change of the above reaction is:

$\Delta H^o_{rxn}=[(8\times \Delta H^o_f_{CO_2(g)})+(10\times \Delta H^o_f_{H_2O(g)})]-[(1\times \Delta H^o_f_{C_4H_{10}(g)})+(4\times \Delta H^o_f_{O_2(g)})]$

We are given:

$\Delta H^o_f_{(C_4H_{10}(g))}=-125.6kJ/mol\\\Delta H^o_f_{(H_2O(g))}=-241.82kJ/mol\\\Delta H^o_f_{(O_2(g))}=0kJ/mol\\\Delta H^o_f_{(CO_2(g))}=-393.5kJ/mol\\\Delta H^o_{rxn}=?$

Putting values in above equation, we get:

$\Delta H^o_{rxn}=[(8\times -393.5)+(10\times -241.82)]-[(2\times -125.6)+(4\times 0)]\\\\\Delta H^o_{rxn}=-5315kJ$

Enthalpy of combustion (per mole) of $C_4H_{10} (g)$ is -2657.5 kJ

6 0

3 years ago

What volume does .0685 mol of gas occupy at STP? 1mole =22.4

GuDViN [60]

V = nRT/P
V = 0.685 mol*(.0821 L*atm/K*mol)*273 K/1 atm

4 0

3 years ago

Read 2 more answers

Explain how the following experimental errors affect the final calculation of the kilocalories per gram for a food item. Be spec

Ainat [17]

Answer:

a) the final kilocalories per gram for food will be less because the mass was reduced

b)the final kilocalories per gram for food will be less since

c) the final kilocalories per gram for food will be less since the reaction will eventually go to completion

d) the final kilocalories per gram for food will be more.

Explanation:

a) the final kilocalories per gram for food will be less because the mass was reduced from 110.3 to 101.3g

b)the final kilocalories per gram for food will be less since some marshmallow fell off before the reaction

c) the final kilocalories per gram for food will be less since the reaction will eventually go to completion

d) the final kilocalories per gram for food will be more since the thermometer that got stuck will add to the value of final kilocalories per gram

6 0

3 years ago

)

Nat2105 [25]

A good reason for a desert fox to show this pattern of behavior because hunting at night allows the fox to use its night vision.

<h3>What is Hunting?</h3>

Thi9s is commonly practised by predators such as fox in which they capture and kill other animals for food.

The fox has a good night vision which makes it able to hunt for animals during the night also. This is why option C is chosen as the most appropriate choice.

Read more about Hunting here brainly.com/question/81175

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2 years ago