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noname [10]
3 years ago
9

The constellations seem to move as the seasons on Earth change. What causes this?

Chemistry
1 answer:
Tomtit [17]3 years ago
8 0
This change<span> is due to the motion of the Earth in its orbit around the Sun. Each day a few stars are visible in the east that were not visible the night before.</span>
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Calculate the molarity of the two solutions.
beks73 [17]

Answer:

A = Molarity = 0.22 M

B = Molarity = 0.36 M

Explanation:

Given data:

For first solution:

number of moles = 0.550 mol

Volume of solution = 2.50 L

Molarity = ?

Molarity:

Formula:

Molarity = number of moles of solute / volume of solution in L.

Molarity = 0.550 mol / 2.50 L

Molarity = 0.22 M

For second solution:

Mass of NaCl =  15.7 g

Volume of solution = 709 mL  or 709/1000 = 0.709 L

Molarity = ?

Solution:

Number of moles = mass / molar mass

Number of moles = 14.7 g/ 58.44 g/mol

Number of moles = 0.252 mol

Molarity:

Molarity = number of moles of solute / volume of solution in L.

Molarity = 0.252 mol / 0.709 L

Molarity = 0.36 M

8 0
3 years ago
Determine the enthalpy for this reaction: Al(OH)3(s)+3HCl(g)→AlCl3(s)+3H2O(l)
ivanzaharov [21]
<span>Important information to solve the exercise :
Substance ΔHf (kJ/mol):
HCl(g)= −92.0 </span><span>kJ/mol
Al(OH)3(s)= −1277.0 </span><span><span>kJ/mol
</span> H2O(l)= −285.8 </span><span>kJ/mol
AlCl3(s) =−705.6 </span><span>kJ/mol

</span><span>Al(OH)3(s)+3HCl(g)→AlCl3(s)+3H2O(l)
    reactants                         products

products- reactants:</span><span>

(−705.6) + (3 x −285.8) - ( −1277.0 ) - (3 x −92.0 ) = - 10.0 </span>kJ per mole at 25°C
<span>
</span>






6 0
3 years ago
Describe the results of Ernest Rutherford's gold-foil experiment and explain how his results changed ideas about the distributio
sashaice [31]
Physicist Ernest Rutherford<span> established the nuclear theory of the atom with his </span>gold-foil experiment<span>. When he shot a beam of alpha particles at a sheet of </span>gold foil<span>, a few of the particles were deflected. He concluded that a tiny, dense nucleus was causing the deflections.</span>
4 0
3 years ago
Read 2 more answers
Two well-known complex ions containing ni are [ni(h2o)6]2+, which is green, and [ni(en)3]2+, which is purple. which one of these
Julli [10]
For [Ni(en)³]²⁺ which is purple, the crystal field splitting energy is greater than the complex ion, [Ni(H₂O)₆]²⁺ which is green in color.
When a Lewis base id attached to the metal ion by covalent bond, then the complex ion is formed and when these complex ions are present with other ions of opposite charge or neutral charge, they will make complex compounds.
7 0
3 years ago
What are some of the main ways to add energy to a reaction? plzzz help
Tresset [83]

Answer:

Heat.

Light.

Sound.

Electricity

Explanation:

4 0
2 years ago
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