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sergeinik [125]

3 years ago

12

Determine the number of protons and neutrons in an isotope of bromine (br) with a mass number/atomic mass of 79. (the atomic num

ber of bromine is 35.)

1 answer:

miskamm [114]3 years ago

8 0

44 neutrons and 35 protons. The number of neutrons you have is equal to the atomic mass minus the atomic number.

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What is the melting point of water?

o-na [289]

the melting point of water is 32 degrees Fahrenheit , 0 degrees Celsius. <span />

6 0

3 years ago

Which response has both answers correct? Will a precipitate form when 250 mL of 0.33 M Na 2CrO 4 are added to 250 mL of 0.12 M A

olchik [2.2K]

Answer:

A precipitate will form.

[Ag⁺] = 2.8x10⁻⁵M

Explanation:

When Ag⁺ and CrO₄²⁻ are in solution, Ag₂CrO₄(s) is produced thus:

Ag₂CrO₄(s) ⇄ 2 Ag⁺(aq) + CrO₄²⁻(aq)

Ksp is defined as:

Ksp = 1.1x10⁻¹² = [Ag⁺]² [CrO₄²⁻]

<em>Where the concentrations [] are in equilibrium</em>

Reaction quotient, Q, is defined as:

Q = [Ag⁺]² [CrO₄²⁻]

<em>Where the concentrations [] are the actual concentrations</em>

<em />

If Q < Ksp, no precipitate will form, if Q >= Ksp, a precipitate will form,

The actual concentrations are -Where 500mL is the total volume of the solution-:

[Ag⁺] = [AgNO₃] = 0.12M ₓ (250mL / 500mL) = 0.06M

[CrO₄²⁻] = [Na₂CrO₄] = 0.33M × (250mL / 500mL) = 0.165M

And Q = [0.06M]² [0.165M] = 5.94x10⁻⁴

As Q > Ksp; a precipitate will form

In equilibrium, some Ag⁺ and some CrO₄⁻ reacts decreasing its concentration until the system reaches equilibrium. Equilibrium concentrations will be:

[Ag⁺] = 0.06M - 2X

[CrO₄²⁻] = 0.165M - X

<em>Where X is defined as the reaction coordinate</em>

<em />

Replacing in Ksp expression:

1.1x10⁻¹² = [0.06M - 2X]² [0.165M - X]

Solving for X:

X = 0.165M → False solution. Produce negative concentrations.

X = 0.0299986M

Replacing, equilibrium concentrations are:

[Ag⁺] = 0.06M - 2(0.0299986M)

[CrO₄²⁻] = 0.165M - 0.0299986M

<h3>[Ag⁺] = 2.8x10⁻⁵M</h3>

[CrO₄²⁻] = 0.135M

6 0

3 years ago

How does cooler air move in relation to warmer air?

ladessa [460]

Answer:
Cool air moves down while hot air rises

7 0

2 years ago

What is the answer?

mixas84 [53]

Answer:

Cranberry juice is a homogeneous mixture.

Explanation:

Cranberry juice is a clear, red liquid. It is a homogeneous mixture, because you can't see a boundary between the water and the dissolved red substances dissolved in the water.

A is wrong. In oatmeal with raisins, you can tell the raisins from the oatmeal (see below).

C is wrong. Milk is a suspension of fat globules in an aqueous solution of other substances

D is wrong. Pepsi in an unopened bottle is a homogeneous, clear brown aqueous solution of carbon dioxide, high fructose corn syrup, and other substances.

7 0

3 years ago

How many calcium atoms in Ca(ClO3)2?

Serjik [45]

Answer:

1

Explanation:

There is only one calcium atom because the subscript 3 applies only to the oxygen. Outside of the parentheses, the subscript 2 only applies to the chlorate ion. Therefore, there is only one calcium atom because there are no coefficients and subscripts. (Also drawing it out will help)

8 0

3 years ago