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2 years ago

8.Based on Kepler’s work, which best describes the orbit of a planet around the Sun?

Chemistry

2 answers:

Zepler [3.9K]2 years ago

4 0

the answer is C. 1.26 days

topjm [15]2 years ago

4 0

For question 10.) the answer is: focus

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The envelope of air that surrounds the earth is called

svlad2 [7]

Atmosphere is the envelope of air that surrounds the earth.

4 0

2 years ago

Which of the following statements describes the law of conservation of mass?

SCORPION-xisa [38]

Explanation:

I think a is correct answer

8 0

2 years ago

For each solution, calculate the initial and final pH after the addition of 0.010 mol of NaOH.

Murljashka [212]

Answer:

A. 12.6

B. 4.05

C. 10.93

Explanation:

A. 0.010mol of NaOH in 250.0mL gives a concentration of 0.04M NaOH = 0.04M OH⁻

pOH = -log [OH⁻] = 1.398

pH = 14-pOH = 12.6

B. The reaction of NaOH with HCHO₂ is:

NaOH + HCHO₂ → H₂O + CHO₂⁻ + Na⁺

Initial moles of CHO₂⁻ and HCHO₂ are:

CHO₂⁻ = 0.250L × (0.275mol/L) = 0.06875moles

HCHO₂ = 0.250L × (0.195mol/L) = 0.04875moles

After reaction:

CHO₂⁻ = 0.06875moles + 0.010mol = 0.07875mol

HCHO₂ = 0.04875moles - 0.010mol = 0.03875mol

Using H-H equation (pKa of this buffer: 3.74)

pH = 3.74 + log [CHO₂⁻] / [HCHO₂]

pH = 3.74 + log [0.07875mol] / [0.03875mol]

pH = 4.05

C. The reaction of NaOH with CH₃CH₂NH₃Cl is:

NaOH + CH₃CH₂NH₃Cl → H₂O + CH₃CH₂NH₂ + Cl⁻ + Na⁺

Initial moles of CH₃CH₂NH₃Cl and CH₃CH₂NH₂ are:

CH₃CH₂NH₃Cl = 0.250L × (0.235mol/L) = 0.05875moles

CH₃CH₂NH₂ = 0.250L × (0.255mol/L) = 0.06375moles

After reaction:

CH₃CH₂NH₃Cl = 0.05875moles - 0.010mol = 0.04875mol

CH₃CH₂NH₂ = 0.06375moles + 0.010mol = 0.07375mol

Using H-H equation (pKa of this buffer: 10.75)

pH = 10.75 + log [CH₃CH₂NH₂] / [CH₃CH₂NH₃Cl]

pH = 10.75 + log [0.07375mol] / [0.04875mol]

pH = 10.93

8 0

2 years ago

Calculate [H3O+] and [OH−] for each of the following solutions at 25 ∘C given the pH. pH= 2.89

dimaraw [331]

Answer: The value of $[H_{3}O^{+}]$ is 0.0012 M and $[OH^{-}]$ is $1.02 \times 10^{-14}$ .

Explanation:

pH is the negative logarithm of concentration of hydrogen ion.

It is given that pH is 2.89. So, the value of concentration of hydrogen ions is calculated as follows.

$pH = - log [H^{+}]\\2.89 = - log [H^{+}]\\conc. H^{+} = 0.0012 M$

The relation between pH and pOH value is as follows.

pH + pOH = 14

0.0012 + pOH = 14

pOH = 14 - 0.0012 = 13.99

Now, pOH is the negative logarithm of concentration of hydroxide ions.

Hence, $[OH^{-}]$ is calculated as follows.

$pOH = - log [OH^{-}]\\13.99 = - log [OH^{-}]\\conc. OH^{-} = 1.02 \times 10^{-14} M$

Thus, we can conclude that the value of $[H_{3}O^{+}]$ is 0.0012 M and $[OH^{-}]$ is $1.02 \times 10^{-14}$ .

6 0

2 years ago

An electromagnetic wave that has a lower frequency than infrared radiation will have ____ than the infrared radiation. longer wa

Monica [59]

Answer: longer wavelength and lower energy.

Explanation:

1) The wavelength is inversely related to the frequency. So, an electromagnetic wave with lower frequency will have longer wavelength.

This is the formula for electromagnetic waves:

λ = c / ν

where λ is the wavelength, c is the speed of light, and ν is the frequency.

2) Energy is directly related to the frequency.

This is the formula E = hν,

where E is the energy, h is Planck constant, and ν is the frequency.

So, the lower the frequency the lower the energy.

3) Conclusion:
An electromagnetic wave that has a lower frequency than infrared radiation will have longer wavelength and lower energy than the infrared radiation

6 0

2 years ago