Which of the following statements is true for an exothermic reaction? The products have higher potential energy than the reactants, and the enthalpy change is negative.
The products have higher potential energy than the reactants, and the enthalpy change is positive.
The products have lower potential energy than the reactants, and the enthalpy change is negative.
The products have lower potential energy than the reactants, and the enthalpy change is positive.

Answers

Answer 1

Answer:

Ans: The products have lower potential energy than the reactants, and the enthalpy change is negative.

In general, chemical reactions can be broadly classified into two categories:

1) Exothermic

2) Endothermic

Exothermic reactionsproceed with the evolution of heat. Here, the reactants have a higher potential energy which is released as the reaction progresses to form products. Consequently, the products are in a lower energy state. Since energy is released, the enthalpy change will be negative.

In contrast, endothermic reactions proceed with the absorption of heat. Here,the products will be in a higher energy state. Since energy is absorbed, the enthalpy change will be positive.

Answer 2

Answer: The enthalpy change for an exothermic reaction is negative because heat is being released, so that takes out two of the responses. Since energy is being released into the surroundings due to the exothermic reaction, the potential energy of the products is lower than that of the reactants. Energy is being put in to make the reaction occur, but then that energy is all being released into the surroundings thus a lower potential energy level for the products

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When sodium metal is added to water, an orange flame is observed on the metal surface. Based on this observation, what can best be concluded

Answers

Answer:

the answer i belive is c

Explanation:

A chemical reaction occurs because heat and light are given off.

Explanation:

A property which causes change in chemical composition of a substance is known as a chemical property. For example, reactivity, toxicity, combustion etc.

Whereas a property which causes no change in chemical composition of a substance is known as a physical property. For example, mass, volume, density etc.

Sodium is a very reactive metal and it reacts readily with oxygen, water etc. So, when sodium is added to water then occurrence of an orange flame represents its reactivity.

Thus, based on given observation it can be concluded that chemical reaction takes place when sodium is added to water.

According to kineric molecular theory which statement descrives the particles in a sample of an ideal gas

Answers

Answer:

According to the kinetic molecular theory, which statement describes the particles in a sample of an ideal gas? The motion of the gas particles is random and in a straight-line.

Explanation:

Consider the reaction of CaC2 and water to produce CaCO3 and NH3 according to the reaction CaCN2 + 3H2O → CaCO3 + 2 NH3 . How much CaCO3 is produced upon reaction of 45 g CaCN2 and 45 g of H2O

Answers

Answer:

16.27 g of CaCO3 are produced upon reaction of 45 g CaCN2 and 45 g of H2O.

Explanation:

Ca(CN)2 + 3H2O → CaCO3 + 2 NH3

First of all, let's find out the limiting reactant.

Molar mass Ca(CN)2.

Molar mass H2O: 18 g/m

Moles of Ca(CN)2: mass / molar mass

45 g / 92.08 g/m = 0.488 moles

Moles of H2O: mass / molar mass

45g / 18g/m = 2.50 moles

This is my rule of three

1 mol of Ca(CN)2 needs 3 moles of H2O

2.5 moles of Ca(CN)2 needs (2.5 . 3) / 1 = 7.5 moles

I need 7.5 moles of water, but I only have 0.488. Obviously water is the limiting reactant; now we can work on it.

3 moles of water __ makes __ 1 mol of CaCO3

0.488 moles of water __ makes ___ (0.488 . 1) / 3 = 0.163 moles

Molar mass CaCO3 = 100.08 g/m

Molar mass . moles = mass

100.08 g/m . 0.163 moles = 16.27 g

Ethene is the first member of the a. Alkane series
b. Alkyne series
c. Saturated hydrocarbons
d. Unsaturated hydrocarbons
e. Aromatic hydrocarbons

Answers

It will be:

b. Alkyne* series

* You have done a spelling mistake here. It will be "Alkene" not "Alkyne".

Which of the following is an oxidation-reduction reaction?Fe2O3 + 3CO mc009-1.jpg 2Fe + 3CO2
CuSO4 + 2NaOH mc009-2.jpg Cu(OH)2 + Na2SO4
2NaOH + H2CO3 mc009-3.jpg Na2CO3 + 2NaOH
Pb(NO3)2 + Na2SO4 mc009-4.jpg 2NaNO3 + PbSO4

Answers

I think the correct answer is the first chemical reaction given. The reaction, Fe2O3 + 3CO = 2Fe + 3CO2, represents an oxidation-reduction reaction. This type of reaction involves the gaining and losing of electrons of the elements involved in a reaction where it is essential that as one is losing some electrons, the other is gaining the electrons lost.

Answer:

The correct option is: Fe₂O₃ + 3CO → 2Fe + 3CO₂

Explanation:

An oxidation-reduction reaction, also known as the redox reaction, is a chemical reaction in which there is simultaneous transfer of electrons from one species to another.

The species that gains electrons gets reduced. Whereas, species that loses electrons gets oxidized.

Among the given options, only reaction 1 is a redox reaction:

Fe₂O₃ + 3CO → 2Fe + 3CO₂

Reason- In this reaction, iron (Fe) gains electrons and gets reduced from +3 oxidation state in Fe₂O₃ to 0 oxidation state in Fe. Whereas, carbon (C) loses electrons and gets oxidized from +2 oxidation state in CO to +4 oxidation state in CO₂.

Since both the oxidation and reduction reactions are occurring simultaneously.

Therefore, it is an redox reaction.

Thermal expansion or thermal contraction would be most noticeable in which of the following?A. Hot car seat
B. Concrete in a sidewalk
C. Air inside a balloon
D. Liquid in a drink

Answers

The answer is C. Air inside a balloon. This is because gases are much more affected by thermal expansion and contraction compared to liquids and solids. The reason behind this is that gas molecules are very loosely packed, so even the slightest changes in temperature have a big effect on its pressure and volume. If the air inside a balloon has a temperature rise, the tendency is for the balloon to expand and potentially explode.

Liquids are also affected by thermal expansion or contraction, but not as much as gases. Solids tend to maintain their shape under thermal expansion or contraction.

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