All categories

3 years ago

Select all the correct answers,

Chemistry

1 answer:

Anastasy [175]3 years ago

7 0

Answer:

The reaction for which ΔH is positive are endothermic reactions.

Explanation:

The energy changes occur during the bonds formation and bonds breaking.

There ere two types of reaction endothermic and exothermic reaction.

Endothermic reactions:

The type of reactions in which energy is absorbed are called endothermic reactions.

In this type of reaction energy needed to break the bond are higher than the energy released during bond formation.

For example:

C + H₂O → CO + H₂

ΔH = +131 kj/mol

it can be written as,

C + H₂O + 131 kj/mol → CO + H₂

You might be interested in

What determines an element's chemical properties

Alik [6]

The three factors determine the chemical properties of an element:
The number and arrangement of electrons in an atom
The number of valence electrons
The number and arrangement of electrons

5 0

2 years ago

Read 2 more answers

A chemist combined 0.440 L of an unknown calcium solution with an excess of ammonium chromate. This resulted in the precipitatio

Rina8888 [55]

The concentration of the original calcium ions is 0.005 M

<h3>What is concentration?</h3>

The term concentration has to do with the amount of substance in solution. We know that the concentration can be measured in a lot of units such as mole/litre, grams per litre, percentage and so on.

As such we have the equation;

Ca^2+(aq) + (NH4)2CrO4(aq) --------> CaCrO4(s) + 2NH4^+(aq)

Number of moles of the precipitate = 346.7 * 10^-3 g/156 g/mol

= 0.0022 moles

Now;

1 mole of Ca^2+ produces 1 mole of CaCrO4 hence 0.0022 moles of CaCrO4 was produced by 0.0022 moles of CaCrO4.

Given that the volume of the solution is 0.440 L, the concentration of the solution is; 0.0022 moles/0.440 L

= 0.005 M

Learn more about molarity:brainly.com/question/8732513

#SPJ1

6 0

1 year ago

Solid carbon (C) can burn in oxygen (O2). Select

babunello [35]

Answer:

OCO

Another way of writing CO₂

Explanation:

A reaction equation has reactants on the left and products on the right.

The reactants are carbon and oxygen. The product is carbon dioxide.

C + O₂ → CO₂

You might see the equation both ways.

C + O₂ → OCO

C + O₂ in the products would mean no reaction has occurred. The problem can solid carbon can burn in oxygen, so a reaction will occur. For no reaction, you would put "NR" in the products.

OCO is the structural way of writing CO₂. Both have one carbon atom (C) and two oxygen atoms (O).

C + 2O is not possible. Oxygen, if alone, has to be at least O₂ because it's a diatomic molecule.

3 0

2 years ago

Exactly 1.0 mol N2O4 is placed in an empty 1.0-L container and is allowed to reach equilibriumdescribed by the equation N2O4(g)↔

Vilka [71]

Answer : The correct option is, (C) 1.1

Solution : Given,

Initial moles of $N_2O_4$ = 1.0 mole

Initial volume of solution = 1.0 L

First we have to calculate the concentration $N_2O_4$ .

$\text{Concentration of }N_2O_4=\frac{\text{Moles of }N_2O_4}{\text{Volume of solution}}$

$\text{Concentration of }N_2O_4=\frac{1.0moles}{1.0L}=1.0M$

The given equilibrium reaction is,

$N_2O_4(g)\rightleftharpoons 2NO_2(g)$

Initially c 0

At equilibrium $(c-c\alpha)$ $2c\alpha$

The expression of $K_c$ will be,

$K_c=\frac{[NO_2]^2}{[N_2O_4]}$

$K_c=\frac{(2c\alpha)^2}{(c-c\alpha)}$

where,

$\alpha$ = degree of dissociation = 40 % = 0.4

Now put all the given values in the above expression, we get:

$K_c=\frac{(2c\alpha)^2}{(c-c\alpha)}$

$K_c=\frac{(2\times 1\times 0.4)^2}{(1-1\times 0.4)}$

$K_c=1.066\aprrox 1.1$

Therefore, the value of equilibrium constant for this reaction is, 1.1

4 0

2 years ago

Which property of water makes it helpful to use in car radiators?

Nezavi [6.7K]

The correct answer is C) Water takes long to heat and cool down than other liquids.

It doesn't climb up the sides of a tube any more than other solutions do, and being a universal solvent has nothing to do with radiators. It does however take a long time to heat and cool down since you don't have a 100+ celsius burner to heat it up in an instant.

5 0

2 years ago