The chemical formula for aluminum hydroxide is Al(Oh)3. How many hydrogen atoms are present in 1 molecule here?

Your teacher asks you to follow the instructions in a lab to produce several known chemical reactions. During these procedures,

vova2212 [387]

Answer:

There are five evidences that tell whether a chemical change has occurred. These are change of color, change of odor, change in temperature or energy, formation of gas and formation of a precipitate.

Explanation:

Chemical Change- This is a type of chemical reaction which occurs when the properties of one or more atoms change and results into a<u> newly formed substance. </u>

Let's have a further discussion of the evidences.

1. Change of Color- Color change is caused by the combination of two or more substance with different molecular structures. A popular example of this is the Statue of the Liberty, which is made of copper plates. Due to the exposure of copper to elements like water, it changed color.

2. Change of Odor- This can be best presented with rotting food. During the rotting process, the food undergoes a chemical reaction. The result is a rotten smell.

3. Change in Temperature or Energy- An example of this is the burning of wood. Its change is considered non-reversible.

4. Formation of Gas- This can be best presented with the cake batter (the one being used to make cakes or pancakes). The batter rises which means it is forming gas. This is caused by the reaction of the baking soda and the acid.

5. Formation of a Precipitate- This occurs when two soluble salts combine and their outcome is an insoluble salt (this is the precipitate).

Take note that if any of these evidences occur, then there's definitely a chemical reaction.

3 0

3 years ago

From the list below, determine which properties are for compounds. I. It takes a large amount of energy to separates the element

marshall27 [118]

All of them are properties of compounds except III.

for I, compounds are chemically combined together, so to separate them, we must use chemical methods like electrolysis or applying heat. These requires large amount of energy.

For II, they're always fixed. For example, in water (H2O), the ratio of hydrogen and oxygen is always 1:8 in mass. If there's some extra added, the substance becomes mixture instead of compounds.

For IV, after you chemically combined elements or compounds together, their properties are completely different. For example, iron can be attracted to magnets, but iron II sulphide does not.

5 0

3 years ago

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How many grams are 1.25 moles of potassium bromide (KBr)?

sukhopar [10]

Answer:

The SI base unit for amount of substance is the mole. one mole is equal to one mole potassium bromide or 119.0023 grams

6 0

3 years ago

Large crystals are formed when _____. igneous rocks cool very quickly metamorphic rocks change into igneous rock sedimentary roc

vivado [14]

igneous rocks cool very slowly

Explanation:

Large crystals are formed when rocks cool very slowly. This gives time for crystallization nuclei to form and other crystals aggregates round it.

Large crystals in rocks are typical of intrusive igneous rocks.
These rocks are formed beneath the earth surface and they usually have big crystals.
This because they cool slowly and have time for crystal formation.
Rocks that cools rapidly are extrusive igneous rocks.
They are usually fine grained and glassy in nature.

learn more:

Volcanic eruptions brainly.com/question/5055821

#learnwithBrainly

3 0

3 years ago

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Predict which of the following pairs of solutions, when mixed together, will cause a precipitate to form. (Select all that apply

Kay [80]

Answer:

25 mL of 1 × 10–5 M Co(NO₃)₂ and 75 mL of 5 × 10–4 M Na₂S

500 mL of 7.5 × 10–4 M AlCl₃ and 100 mL of 1.7 × 10–5 M Hg₂(NO₃)₂.

650 mL of 0.0080 M K₂SO₄ and 175 mL of 0.15 M AgNO₃

Explanation:

When 2 compounds that produce an insoluble substance are mixed together, <em>A precipitate will be formed if Q of reaction > Ksp</em>

For the solutions:

1.5 L of 0.025 M BaCl₂ and 1.25L of 0.014 M Pb(NO₃)₂.

Ksp is:

PbCl₂(s) ⇄ Pb²⁺(aq) + 2Cl⁻(aq)

Ksp = 2.4x10⁻⁴ = [Pb²⁺][Cl⁻]²

Molar concentration of each ion is:

[Pb²⁺] = 1.25L ₓ (0.014mol / L) = 0.0175mol / 2.75L = 6.36x10⁻³M

[Cl⁻] = 2 ₓ 1.5L ₓ (0.025mol / L) = 0.075mol / 2.75L = 0.0273M

Replacing in Ksp expression to find Q:

Q = [6.36x10⁻³M][0.0273M]² = 4.73x10⁻⁶

As Q < Ksp, the mixture will not produce a precipitate.

25 mL of 1 × 10–5 M Co(NO₃)₂ and 75 mL of 5 × 10–4 M Na₂S

Ksp is:

CoS(s) ⇄ Co²⁺(aq) + S²⁻(aq)

Ksp = 4.0x10⁻²¹ = [Co²⁺][S²⁻]

Molar concentration of each ion is:

[Co²⁺] = 0.025L ₓ (1x10⁻⁵mol / L) = 2.5x10⁻⁷mol / 0.1L = 2.5x10⁻⁶M

[S²⁻] = 0.075L ₓ (5x10⁻⁴mol / L) = 3.75x10⁻⁵mol / 0.1L = 3.75x10⁻⁴M

Replacing in Ksp expression to find Q:

Q = [2.5x10⁻⁶M][3.75x10⁻⁴M] = 9.38x10⁻⁶

As Q > Ksp, the mixture will produce a precipitate.

500 mL of 7.5 × 10–4 M AlCl₃ and 100 mL of 1.7 × 10–5 M Hg₂(NO₃)₂.

Ksp is:

Hg₂Cl₂(s) ⇄ 2Hg⁺(aq) + 2Cl⁻(aq)

Ksp = 3.5x10⁻¹⁸ = [Hg⁺]²[Cl⁻]²

Molar concentration of each ion is:

[Hg⁺] = 2ₓ0.100L ₓ (1.7x10⁻⁵mol / L) = 3.4x10⁻⁶mol / 0.6L = 5.67x10⁻⁶M

[Cl⁻] = 3 ₓ 0.500L ₓ (7.5x10⁻⁴mol / L) = 1.125x10⁻³mol / 0.6L = 1.88x10⁻³M

Replacing in Ksp expression to find Q:

Q = [5.67x10⁻⁶M]²[1.88x10⁻³M]² = 1.14x10⁻⁶

As Q > Ksp, the reaction will produce a precipitate.

650 mL of 0.0080 M K₂SO₄ and 175 mL of 0.15 M AgNO₃

Ksp is:

Ag₂SO₄(s) ⇄ 2Ag⁺(aq) + SO₄²⁻(aq)

Ksp = 1.5x10⁻⁵ = [Ag⁺]²[SO₄²⁻]

Molar concentration of each ion is:

[Ag⁺] = 0.175L ₓ (0.15mol / L) = 0.02625mol / 0.825L = 0.0318M

[SO₄²⁻] = 0.650L ₓ (0.080mol / L) = 0.052mol / 0.825L = 0.0630M

Replacing in Ksp expression to find Q:

Q = [0.0318M]²[0.0630M] = 6.37x10⁻⁵

As Q > Ksp, the reaction will produce a precipitate.

6 0

3 years ago