The electron affinity of Bi is -94.6 kJ and the value for At is -280 kJ. What is the approximate electron affinity for Po?

1) The heat of combustion for the gases hydrogen, methane and ethane are −285.8, −890.4 and −1559.9 kJ/mol respectively at 298K.

Morgarella [4.7K]

Answer:

The enthalpy of the reaction is 64.9 kJ/mol.

Explanation:

$H_2 + \frac{1}{2}O_2\rightarrow H_2O,\Delta H_1 =-285.8 kJ$ ..[1]

$CH_4 + 2O_2\rightarrow CO_2 + 2H_2O,\Delta H_2 =-890.4 kJ$ ..[2]

$C_2H_6 + \frac{7}{2}O_2\rightarrow 2CO_2 + 3H_2O,\Delta H_3= -1559.9 kJ$ ..[3]

$2CH_4(g)\rightarrow C_2H_6(g) + H_2(g),\Delta H_4=?$ ..[4]

2 × [2] - [1]- [3] = [4] (Using Hess's law)

$\Delta H_4=2\times \Delta H_2 -\Delta H_1 -\Delta H_3$

$\Delta H_4=2\times (-890.4 kJ)-(-285.8 kJ) -(-1559.9 kJ)$

$\Delta H_4=64.9 kJ/mol$

The enthalpy of the reaction is 64.9 kJ/mol.

3 0

3 years ago

Classify the following reactions: HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l)HCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l) Ba(OH)2(aq)+ZnCl2(aq)→BaCl2(a

Savatey [412]

The reactions are

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)

Ba(OH)2(aq) + ZnCl2(aq) → BaCl2(aq) + Zn(OH)2(s)

2AgNO3(aq) + Mg(s) → Mg(NO3)2(aq) + 2Ag(s)

Answer:

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) = Acid-base reaction

Ba(OH)2(aq) + ZnCl2(aq) → BaCl2(aq) + Zn(OH)2(s) = Precipitation reaction

2AgNO3(aq) + Mg(s) → Mg(NO3)2(aq) + 2Ag(s) = Redox reaction

Explanation:

HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l) .

The reaction above is an example of an acid-base reaction. Acid-base reaction is a chemical reaction between an acid and a base. The product is usually a salt and water. An acid dissolves in water to produce H+ ion. Hydrochloric acid is a strong acid as it is completely dissociated in water. A base dissolves in water to form hydroxide ion(OH-). The sodium hydroxide is a strong base as it completely dissociate in water. The reaction between a base and an acid can be known as a neutralization reaction.

Ba(OH)2(aq) + ZnCl2(aq) → BaCl2(aq) + Zn(OH)2(s)

The reaction above is a precipitation reaction. Precipitation reaction is a reaction where two ionic bonds or cations and anions in an aqueous solution react to form an insoluble salts. The insoluble salt formed is known as the precipitate. The reaction above is an example of a double replacement reaction. From the equation the ions replace each other depending on the cations and anions. They switch partners as both reactants lose their partners to form new partnership with a different ion. The two reactants ( Ba(OH)2 and ZnCl2 ) are aqueous solution, they react to from a solid precipitates( Zn(OH)2(s) ).

2AgNO3(aq) + Mg(s) → Mg(NO3)2(aq) + 2Ag(s)

The reaction is known as an oxidation-reduction reaction(Redox reaction). A oxidation-reduction reaction their is a transfer of electron(s) between two species. The oxidation number of a chemical reaction changes by losing or gaining electrons. One of the reactant is a reducing agent and the other is an oxidizing agent.

From the reaction Mg is the reducing agent and AgNO3 is the oxidizing agents.

2 Ag+ + 2 e- → 2 Ag∧0 (reduction)

Mg∧0 - 2 e- → Mg²+ (oxidation)

8 0

4 years ago

Select 2-possible ointment bases. Select one or more:

fredd [130]

Answer:

The correct option is: c. petroleum jelly, d. Polyethylene glycol 4000/600 mixture

Explanation:

Topical medications are used for the treatment of ailments and include ointments, gels, lotions creams etc. that can applied directly on the surface of the body i.e. skin.

An ointment base medication gets rapidly absorbed into the skin. Some of the examples of <u>ointment bases</u> include water-soluble bases: <u>polyethylene glycol</u>, hydrocarbon bases: <u>petroleum jelly</u>, paraffin wax.

7 0

3 years ago

HELP ME AND PLZ ANSWERED THIS ALL RIGHT PLZ

Sunny_sXe [5.5K]

<h2>Question no 1:</h2><h2>Answer:</h2>

The correct answer is option A which is Sarah is correct because genetic diversity occurs over a long period of time.

<h3>Explanation:</h3>

Genetic diversity is a large number of allelic combinations for a trait in specie in a population.
Genetic diversity is caused due to mutations or random breeding in a specie.
It is good for the adaptation of specie in an environment, due to diverse in genotypes and phenotype of a trait.

<h2>Question number 2:</h2><h2>Answer:</h2>

The correct answer is option B which is the species will adapt to the changes.

<h3>Explanation:</h3>

Adaptation to an environment means changing your body in such a way to reduce the harmful affects of changing the environment on the body.
For example, the long and thick fur of sheeps in a snowy area will protect them from cold.
If the environment changes, the first thing a specie do is an adaptation to that change in the environment.

<h2>Question 3.</h2><h2>Answer:</h2>

The correct answer is option D which is, "The spines of a cactus protect it from animals".

<h3>Explanation:</h3>

Adaptation to an environment means changing your body in such a way to reduce the harmful affects of changing the environment on the body.
For example, the long and thick fur of sheeps in a snowy area will protect them from cold.
So the plant of cactus was in danger due to animals. So the start growing spines in response to animals.
Hence the correct answer is option D.

<h2>Question 4.</h2><h2>Answer:</h2>

The correct answer is option B which is, "Marie's plant will lean toward the sun so that it can get the most sunlight".

<h3>Explanation:</h3>

The plant will lean towards the sun light by the mechanism of phototropism.
Phototropism is the mechanism of growth of the plant in a specific direction in the response of light.
There are two types of phototropism.
One is a positive phototropism in which plant grows towards the light.
The other is negative phototropism in which plant grows away from the light.
In this question,the plant will do positive tropism.

<h2>Question no. 5</h2><h2>Answer:</h2>

The correct answer is option B which is, "The dodo bird could not adapt quickly to the challenges of the environment".

<h3>Explanation:</h3>

Adaptation to an environment means changing your body in such a way to reduce the harmful affects of changing the environment on the body.
For example, the long and thick fur of sheeps in a snowy area will protect them from cold.
So the dodo could not adopt to the environment. For the positive adaption of survival, they should be afraid of sailors but the would not afraid of a sailor.
Due to which they went extinct.

Remaining questions are in attached document.

Download pdf

7 0

3 years ago

List the ions in solution in the electrolysis of conc.sodium chloride<br>

Licemer1 [7]

Chloride ions Cl –(aq) (from the dissolved sodium chloride) are discharged at the positive electrode as chlorine gas, Cl 2(g) sodium ions Na +(aq) (from the dissolved sodium chloride) and hydroxide ions OH –(aq) (from the water) stay behind - they form sodium hydroxide solution, NaOH(aq)

5 0

3 years ago