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3 years ago

In your own words, define:

Chemistry

1 answer:

vodomira [7]3 years ago

8 0

Hey there!

1.)

The law of conservation of mass states that matter cannot be created or destroyed. This means in a chemical reaction, the products must be equal to the reactants.

2.)

In a balanced chemical equation, there are the same amount of each type of atom, or element, on each side. The products must be equal to the reactants to follow the law of conservation of mass.

3.)

When a chemical reaction occurs, we can see evidence such as bubbles, odor, color change, and heat/light being released. These all are signs that a new substance is being formed.

Hope this helps!

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a chemist dissolved an 11.9-g sample of koh in 100.0 grams of water in a coffee cup calorimeter. when she did so, the water temp

Snowcat [4.5K]

The heat of solution is -51.8 kJ/mol

<h3>What is the heat of solution?</h3>

We know that in a calorimeter, there is no loss or gain of energy. It is a good example of a closed system.

Number of moles of KOH = 11.9-g/56 g/mol = 0.21 moles

Temperature rise = 26.0 ∘c

Mass of the water = 100.0 grams

Heat capacity = 4.184 j/g⋅°c

Then;

ΔH = mcθ

ΔH = 100g * 4.184 j/g⋅°c * 26.0 ∘c = 10.88 kJ

Heat of solution = -(10.88 kJ/ 0.21 moles) = -51.8 kJ/mol

Learn more about heat of solution:brainly.com/question/24243878

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1 year ago

How many bromine are in 6NaBr?

OleMash [197]

6 sodium and 6 Bromine in 6NaBr

5 0

2 years ago

Why do different isotopes of an element generally have the same physical and chemical properties?

tresset_1 [31]

Answer:

The correct answer is because they have same number of protons but different number of neutrons.

Explanation:

Isotopes are atoms of the same element but differ only in the number of neutrons in the nucleus, i.e. they have same atomic number but different mass number.

Mass number is affected as they have different number of neutrons, thus effecting their physical properties.

The number of electrons and protons are same, i.e. their atomic number is same and thus their chemical properties are same as chemical properties are determined by the atom’s electronic configuration and that relates to number of protons.

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3 years ago

A scientist measures the standard enthalpy change for the following reaction to be 67.9 kJ:

bekas [8.4K]

Answer: The standard enthalpy of formation of $H_2O(g)$ is -252.1 kJ/mol.

Explanation:

The balanced chemical reaction is,

$Fe_2O_3(s)+3H_2(g)\rightarrow 2Fe(s)+3H_2O(g)$

The expression for enthalpy change is,

$\Delta H=[n\times H_f_{products}]-[n\times H_f_{reactantss}]$

Putting the values we get :

$\Delta H=[2\times H_f{Fe}+3\times H_f{H_2O}]-[1\times H_f{Fe_2O_3}+3\times H_f{H_2}]$

$67.9kJ=[(2\times 0)+(3\times H_f{H_2O})]-[(1\times -824.2kJ/mol)+3\times 0kJ/mol)]$

$H_f{H_2O}=-252.1kJ/mol$

Thus standard enthalpy of formation of $H_2O(g)$ is -252.1 kJ/mol.

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2 years ago

Putting rock salt on the roads during a snowstorm is an example of: A. Boiling point elevation B. Vapor pressure raising C. Vapo

kvv77 [185]

Answer:

The correct answer is - D. Freezing point depression.

Explanation:

When rock salt is spread over snow-covered icy roads, it generates a liquid layer over it by melting from the surface thereby lowering or depression in the freezing point below the ice.

Therefore, due to this liquid layer comes into the contact with the ice present on the road and causes other ice to melts. This keeps on decreasing the volume of the ice on the road therefore, rock salts spread on the roads during a snowstorm.

7 0

2 years ago