Two different liquids are mixed together. Which observation indicates that an exothermic chemical reaction has taken place?

3. When the hydronium ion concentration of a solution is 1x10-4 M, What

rewona [7]

Answer:

pH = 4

Solution is acidic

Explanation:

Given data;

Hydronium ion concentration = 1 × 10⁻⁴ M

pH of solution = ?

Solution:

pH = -log [H₃O⁺]

pH = -log [ 1 × 10⁻⁴ ]

pH = 4

According to pH scale the pH 7 is neutral while the pH less than 7 is acidic and greater than 7 is basic. The given solution has pH 4 it means solution is acidic.

7 0

3 years ago

HELP!!!! A glass flask containing 100 milliliters of water is sealed with a rubber stopper and placed on a burner. After a while

kondor19780726 [428]

Answer: A closed system, because energy can enter or leave the container, but the water molecules cannot

Explanation:

Open system: In this system energy and matter both have access to their surroundings beyond the boundaries of system. .

Closed system :In this type system only energy has an access to its surroundings beyond the boundaries of system but not matter.

Isolated system:In this type system exchange of both energy and matter are restricted to move outside the boundaries of system.

According to question, the system given is a closed system because energy is transferred from the burner to glass flask and from the glass flask to the water (matter). But water molecules are only getting condensed on the inside surface of the flask that is exchange of matter beyond the boundaries of the system is restricted. Hence, closed system ,A closed system, because energy can enter or leave the container, but the water molecules cannot.

7 0

3 years ago

A 33.0 mL sample of 1.15 M KBr and a 59.0 mL sample of 0.660 M KBr are mixed. The solution is then heated to evaporate water unt

Oksi-84 [34.3K]

Answer:

We need 13.06 grams of silver nitrate to precipitate out silver bromide in the final solution

Explanation:

Step 1: Data given

Sample 1: The 1.15 M sample has a volume of 33.O mL

Sample 2: The 0.660 M sample has a volume of 59.0 mL

Molar mass of KBr = 119 g/mol

Molar mass of AgNO3 = 169.87 g/mol

Step 2: Calculate number of moles for both samples

Number of moles = Molarity * Volume

Sample 1: 1.15 M * 33 *10^-3 L = 0.03795 moles

Sample 2: 0.660 M *59*10^-3 L = 0.03894 moles

Total mol KBr = 0.03795 + 0.03894 = 0.07689 moles

Step 3: Calculate total mass

mass = Number of moles * Molar mass

mass = 0.07689 moles * 119 g/moles = 9.15 grams ( in 55mL)

Step 4: Calculate moles of AgBr

AgNO3 reacts with KBr

KBr(aq) + AgNO3(aq) → AgBr(s) + KNO3(aq)

1 mole of KBr consumed, needs 1 mole of AgNO3 to produce 1 mole of AgBr and 1 mole of KNO3

So 0.07689 moles of KBr wll need 0.07689 moles of AgNO3

Step 5: Calculate mass of silver nitrate

mass of AgNO3 = Moles of AgNO3 * Molar mass of AgNO3

mass of AgNO3 = 0.07689 moles * 169.87 g/mol = 13.06 grams

We need 13.06 grams of silver nitrate to precipitate out silver bromide in the final solution

8 0

3 years ago

Group 18 noble gases are relatively inert because *

choli [55]

Answer:I believe its A. There noble gasses so there happy with there electron count!

Explanation:

3 0

3 years ago

Which of the following chemical equations proves that the law of conservation of mass is in effect?

bogdanovich [222]

Answer:

2KCl + F₂ → 2KF + Cl₂

Explanation:

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

This law was given by French chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

2KCl + F₂ → 2KF + Cl₂

In this equation mass of reactant and product is equal. There are 2 potassium 2 chlorine and fluorine atoms on both side of equation it means mass remain conserved.

All other options are incorrect because mass is not conserved.

Mg₂ + LiBr ---> LiMg + Br

In this equation mass of magnesium is more on reactant side.

Na +O₂ ---> Na₂O

In this equation there is more oxygen and less sodium on reactant side while there is more sodium and less oxygen on product side.

H₂O ---> H₂ + O₂

In this equation there is less oxygen on reactant side while more oxygen on product side.

5 0

3 years ago