Answer is: an instant ice pack becoming cold, splitting a gas molecule and baking bread.

<span>Endothermic reaction is chemical reaction that absorbs more energy than it releases.
</span>In ice pack, <span>reaction absorbs heat from the surroundings (endothermic reaction), lowering the surrounding temperature.
For splitting molecule and baking bread we must add energy to break bonds between atoms.</span>

6 0

2 years ago

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What is the pH of a<br> 2.5 x 10-5 M solution<br> of HCI?

aalyn [17]

Answer:

The pH of the solution is 4.60.

Explanation:

The pH gives us an idea of the acidity or basicity of a solution. More precisely, it indicates the concentration of H30 + ions present in said solution. The pH scale ranges from 0 to 14: from 0 to 7 corresponds to acid solutions, 7 neutral solutions and between 7 and 14 basic solutions. It is calculated as:

pH = -log (H30 +)

pH= -log (2,5 x 10-5)

7 0

2 years ago

An ionic bond occurs between what particles?

atroni [7]

Answer:

A positive and negative ion.

Explanation:

Ionic bond:

It is the bond which is formed by the transfer of electron from one atom to the atom of another element.

Both bonded atoms have very large electronegativity difference.

The atom with large electronegativity value accept the electron from other with smaller value of electronegativity.

For example:

Sodium chloride is ionic compound. The electronegativity of chlorine is 3.16 and for sodium is 0.93. There is large difference is present. That's why electron from sodium is transfer to the chlorine. Sodium becomes positive and chlorine becomes negative ion. Sodium have one valance electron while chlorine have 7 valance electrons. In order to complete the octet chlorine require one electron while sodium need to lose its one electrons. That's why when both atom combine sodium lose its electron and becomes positive ion i.e cation while chlorine accept its electron and becomes negative ion called anion and bond between them is ionic bond.

4 0

3 years ago

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1) A potassium carbonate hydrate has a formula K2CO3.XH2O. 10g of the hydrate leave 7.83g of anhydrous salt upon heating. Deduce

OLEGan [10]

The formula of the hydrated potassium carbonate salt is K₂CO₃.2H₂O

Based on the calculated mass ratio of carbon and oxygen in carbon dioxide, carbon has a fixed composition.

<h3>What are hydrated compounds?</h3>

Hydrated compounds are compounds that contain one or more molecules of water physically combined with a molecule of the compound.

The formula of the hydrated potassium carbonate salt is determined as follows:

Mass of the hydrated sample = 10.0 g

Mass of anhydrous salt = 7.83

mass of water = 10 - 7.83

mass of water = 2.17 g

Molar mass of water = 18.0 g

Molar mass of anhydrous potassium carbonate = 138 g

moles of anhydrous potassium carbonate in sample = 7.83/138

moles of anhydrous potassium carbonate = 0.056 moles

moles of water in the hydrated salt = 2.17/18

moles of water in the hydrated salt = 0.12

Mole ratio of water to anhydrous salt = 0.12/0.056

Mole ratio of water to anhydrous salt = 1 : 2

Formula of hydrated salt = K₂CO₃.2H₂O

The mass ratio of carbon to oxygen in the compounds is given below:

Sample 1:

Mass ratio = 3.62 / (13.26 - 3.62)

Mass ratio = 0.38 : 1

Sample 2:

Mass ratio = 5.91 / (21.66 - 5.91)

Mass ratio = 0.38 : 1

Sample 3:

Mass ratio = 7.07 / (25.91 - 7.07)

Mass ratio = 0.38 : 1

Carbon has a fixed composition.

Learn more about hydrated compounds at: brainly.com/question/11112492

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6 0

1 year ago