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kozerog [31]
3 years ago
13

I need help please i need it today

Chemistry
1 answer:
creativ13 [48]3 years ago
8 0

Answer:

what help.....

i don't understand your question what help....

can you told me what help...

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5. How can you tell the difference between CuS and Cu2S
puteri [66]

Answer:

Density, melting point. and magnetic properties  

Explanation:

I can think of three ways.

1. Density

The density of Cu₂S is 5.6 g/cm³; that of CuS is 4.76 g/cm³.

It should be possible to distinguish these even with high school equipment.

2. Melting point

Cu₂S melts at 1130 °C (yellowish-red); CuS decomposes at 500 °C (faint red).

A Bunsen burner can easily reach these temperatures.

3. Magnetic properties

You can use a Gouy balance to measure the magnetic susceptibilities.

In Cu₂S the Cu⁺ ion has a d¹⁰ electron configuration, so all the electrons are paired and the solid is diamagnetic.

In CuS the Cu²⁺ ion has a d⁹ electron configuration, so all there is an unpaired electron and the solid is paramagnetic.

A sample of Cu₂S will be repelled by the magnetic field and show a decrease in weight.

A sample of CuS will be attracted by the magnetic field and show an increase in weight.

In the picture below, you can see the sample partially suspended between the poles of an electromagnet.

 

6 0
3 years ago
If you start with 0.30 m mn2 , at what ph will the free mn2 concentration be equal to 4.6 x 10-11 m?
aksik [14]

If you start with 0.30 m Mn₂ , at 12.5 pH, free Mn₂ concentration be equal to 4.6 x 10⁻¹¹ m

Initial molarity of Mn₂ = 0.30 M

Final molarity of Mn₂ = 4.6 x 10⁻¹¹

pH = ?

Ksp [Mn(OH)₂] = 4.6 x 10⁻¹⁴ (standard value)

Write the ionic equation

    Mn(OH)₂   →    Mn⁺² + 2OH⁻

    [Mn⁺²] = 4.6 x 10⁻¹¹

We will calculate the concentration of OH⁻ by using Ksp expression

    Ksp = [Mn⁺²][OH-]²

    [Mn⁺²][OH⁻]² = 4.6 x 10⁻¹⁴

    [OH⁻]² = 4.6 x 10⁻¹⁴ / 4.6 x 10⁻¹¹

    [OH⁻]² = 10⁻³

    [OH⁻] = (10⁻³)¹⁽²

    [OH⁻] = 0.0316 M

Calculate the pOH

    pOH = -log [OH⁻]

    pOH =  -log [0.0316]

    pOH = 1.5

Now calculate pH

   pH = 14 - pOH

   pH = 14 - 1.5

   pH = 12.5

You can also learn about molarity from the following question:

brainly.com/question/14782315

#SPJ4

7 0
1 year ago
Which of the following is considered a transition metal?
tatyana61 [14]
Sodium is considered to be a transitional metal
4 0
3 years ago
Read 2 more answers
When an arrhenius base is placed in h20 the only negative ion present in the solution is?
melamori03 [73]
According to Arrhenius theory of acid and base, Acids are those substances which when dissolved in water produces protons, while, Bases are those substances which when dissolved in water produces Hydroxyl Ions.

Example of Arrhenius Bases:

                         
NaOH ₍s₎ → Na⁺ ₍aq₎  +  ⁻OH ₍aq₎

                         LiOH ₍s₎ → Li⁺ ₍aq₎  +   ⁻OH ₍aq₎
Result:
           The only negative ion produced in water when Arrhenius Base is dissolved is ⁻OH (Hydroxyl Ion).
5 0
3 years ago
Skeletal muscle is controlled by the organism.
rosijanka [135]

Some of the muscle attached to the skeleton is voluntary and may be used for movement.

4 0
3 years ago
Read 2 more answers
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