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2 years ago

Which one of the following statements BEST describes a chemical reaction?

Chemistry

1 answer:

Natalija [7]2 years ago

8 0

Answer: The correct statement is (A new substance is formed and the process can usually NOT be undone.)

Explanation:

A chemical reaction is simply defined as the reaction between two or more elements in which a new substance is formed and the process can usually not be undone. Different types of chemical reaction includes:

-- combination reaction: this occurs when two or more reactants form a product. For example: In the burning of coal, It combines with oxygen to produce carbon dioxide. Also in the burning of wood, carbon dioxide is given off and ashes are formed. Because new substance is being formed, they often can't be undone. The ashes formed can't be changed back into wood. Other types of chemical reaction are listed below.

-- Decomposition reaction

-- Single displacement reaction

-- Double displacement reaction

-- combustion reaction

-- Redox reaction

For the product of a chemical reaction to be undone (reversed), it has to undergo another chemical process different from the one that produced it.

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How many molecules are in 3.0 moles of water

diamong [38]

Hopefully this will help you my friend.

7 0

3 years ago

A cubic piece of platinum metal (specific heat capacity = 0.1256 J/°C･g) at 200.0°C is dropped into 1.00 L of deuterium oxide ('

polet [3.4K]

Answer:

$a=5.65cm$

Explanation:

Hello,

In this case, for this heat transfer process in which the heat lost by the hot platinum is gained by the cold deuterium oxide based on the equation:

$Q_{Pt}=-Q_{Deu}$

We can represent the heats in terms of mass, heat capacities and temperatures:

$m_{Pt}Cp_{Pt}(T_f-T_{Pt})=-m_{Deu}Cp_{Deu}(T_f-T_{Deu})$

Thus, we solve for the mass of platinum:

$m_{Pt}=\frac{-m_{Deu}Cp_{Deu}(T_f-T_{Deu})}{Cp_{Pt}(T_f-T_{Pt})} \\\\m_{Pt}=\frac{-1.00L*1110g/L*4.211J/(g\°C)*(41.9-25.5)\°C}{0.1256J/(g\°C)*(41.9-200.0)\°C} \\\\m_{Pt}=3860.4g$

Next, by using the density of platinum we compute the volume:

$V_{Pt}=\frac{3860.4g}{21.45g/cm^3}\\ \\V_{Pt}=180cm^3$

Which computed in terms of the edge length is:

$V=a^3$

Therefore, the edge length turns out:

$a=\sqrt[3]{180cm^3}\\ \\a=5.65cm$

Best regards.

6 0

3 years ago

What is an internal cost of driving a domestic car?

Nataly_w [17]

Answer:

The correct option is: Cost of materials used in manufacture

Explanation:

There are two types of costs of an object: the internal costs and the external costs.

The internal cost of an object is the direct monetized cost. It refers to the cost involved in the <u>production or manufacturing of a given objec</u>t. Example: labor, <u>material required</u>, equipment, energy, and overhead expenses.

3 0

2 years ago

What is the density of the continental crust?

Fiesta28 [93]

Answer: Getting into the technicalities, the continental crust has a density of around 3.0 g/cm3 compared to 2.6 g/cm3 of the continental crust. In addition, the continental crust is much thicker than the oceanic crust.

Explanation:

Hope this helps! Mark me Brainliest pls :)

5 0

2 years ago

Given the following reaction:

mojhsa [17]

Answer:

Option D. 17.5

Explanation:

Equiibrium is: CO + 2H₂ ⇄ CH₃OH

1 mol of CO is in equibrium with 2 moles of hydrogen in order to make, methanol.

Initially we have 0.42 moles of CO and 0.42 moles of H₂

If 0.29 moles of CO remained, (0.42 - 0.29) = 0.13 moles have reacted.

So in the equilibrium we may have:

0.29 moles of CO, and (0.42 - 0.13 . 2) = 0.16 moles of H₂

Ratio is 1:2, if 0.13 moles of CO haved reacted, (0.13 . 2) moles have reacted of hydrogen

Finally 0.13 moles of methanol, are found after the equilibrium reach the end.

Let's make expression for KC: [Methanol] / [CO] . [Hydrogen]²

0.13 / (0.29 . 0.16²)

Kc = 17.5

4 0

3 years ago