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marin [14]
3 years ago
11

Classify each process as either physical or a chemical change.

Chemistry
1 answer:
Dafna11 [192]3 years ago
7 0

Answer:

I think they are all correct

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Which of the following changes
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Exothermic reactions
5 0
3 years ago
How many moles is 1.25 x 1024 atoms of bromine?
Irina-Kira [14]

Answer:

2.08 moles (3 s.f.)

Explanation:

number of moles

= number of atoms ÷ Avogadro's constant

Avogadro's constant= 6.022 ×10²³

Thus, number of moles

= 1.25×10²⁴ ÷ (6.022 ×10²³)

= 2.08 moles (3 s.f.)

8 0
3 years ago
An element has a half-life of 30 years. if 1.0 mg of this element decays over a period of 90 years, how many mg of this element
labwork [276]

Answer:

144.6

Explanation:

6 0
3 years ago
<img src="https://tex.z-dn.net/?f=H_2PO_4%5E-%28aq%29%20%5Crightarrow%20H%5E%2B%28aq%29%20%2B%20HPO_4%5E%7B2-%7D%28aq%29" id="Te
klasskru [66]

Answer:

The pH of the buffer solution = 8.05

Explanation:

Using the Henderson - Hasselbalch equation;

pH = pKa₂ + log ( [HPO₄²-]/[H₂PO4⁻]

where pKa₂ = -log (Ka₂) = -log ( 6.1 * 10⁻⁸) = 7.21

Concentration of OH⁻ added = 0.069 M (i.e. 0.069 mol/L)

[H₂PO4⁻] after addition of OH⁻ = 0.165 - 0.069 = 0.096 M

[HPO₄²-] after addition of OH⁻ = 0.594 + 0.069 = 0.663 M

Therefore,

pH = 7.21 + log (0.663 / 0.096)

pH = 7.21 + 0.84

pH = 8.05

4 0
3 years ago
I really need help pls, will pay anything
Triss [41]

Explanation:

For the first part,

 Reaction equation:

         N₂  +  3H₂   →   2NH₃

Given:

Number of moles of NH₃  = 6 moles

Unknown:

Number of moles of N₂  = ?

Solution:

   N₂  +  3H₂   →   2NH₃;

  From the reaction above, we solve from the known specie to the unknown. Ensure that the equation is balanced;

         2 moles of NH₃ is produced from 1 mole of N₂

        6 moles of NH₃ will be produced from \frac{6}{2}  mole of N₂

                                                                      = 3moles of N₂

The number of moles of N₂ is 3 moles

ii.

Given parameters:

Number of moles of sulfur = 2.4moles

Molar mass of sulfur  = 32.07g/mol

Unknown:

Mass of sulfur  = ?

Solution:

The number of moles of any substance can be found using the expression below;

 Number of moles  = \frac{mass}{molar mass}

  Mass of sulfur  = number of moles of sulfur x molar mass

Insert the parameters and solve;

    Mass of sulfur  = 2.4 x 32.07  = 76.97g

6 0
2 years ago
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