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3 years ago

15

Find the velocity of a swimmer who swims exactly 220 m toward the shore in 72 s.

1 answer:

Aleksandr-060686 [28]3 years ago

5 0

Answer: 3.06m/s

Explanation:

Distance covered by swimmer = 220 m

Time taken by swimmer = 72 s.

Velocity = ?

Recall that velocity is the rate of change of distance per unit time. it is measured in metres per second.

Velocity = Distance / time taken

Velocity = 220m / 72seconds

Velocity = 3.055 m/s (approximate to 3.06m/s)

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3 years ago

Use the Henderson-Hasselbalch equation, eq. (3), to calculate the pH expected for a buffer solution prepared from this acid and

notka56 [123]

Answer:

$pH=4.56$

Explanation:

Hello there!

In this case, given the Henderson-Hasselbach equation, it is possible for us to compute the pH by firstly computing the concentration of the acid and the conjugate base; for this purpose we assume that the volume of the total solution is 0.025 L and the molar mass of the sodium base is 234 - 1 + 23 = 256 g/mol as one H is replaced by the Na:

$n_{acid}=\frac{0.2g}{234g/mol}=0.000855mol\\\\n_{base}= \frac{0.2g}{256g/mol}=0.000781mol$

And the concentrations are:

$[acid]=0.000855mol/0.025L=0.0342M$

$[base]=0.000781mol/0.025L=0.0312M$

Then, considering that the Ka of this acid is 2.5x10⁻⁵, we obtain for the pH:

$pH=-log(2.5x10^{-5})+log(\frac{0.0312M}{0.0342M} )\\\\pH=4.60-0.04\\\\pH=4.56$

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2 years ago

What is the (a) frequency and (b) wavelength (in nm) of a source of purple light at the edge of the visible light spectrum?

stiv31 [10]

Answer: a) $Frequency=666\times10^{12}Hz-789\times10^{12}Hz$

b) $Wavelength=380nm-450nm$

Explanation: Visible light is a form of electromagnetic wave.

Wavelength is defined as the distance between two successive crests of a wave. It is represented as symbol $\lambda$ .

Frequency is defined as the number of complete cycles happening per second. It is represented by the symbol $\nu$ .

Wavelength and Frequency follow inverse relation,

$\nu=\frac{c}{\lambda}$

where, c = speed of light = $3\times10^8m/s$

Wavelength and frequency of a wave is usually expressed in a range.

a) $\text{Frequency of visible light}=666\times10^{12}Hz-789\times10^{12}Hz$

b) $\text{Wavelength of visible light}=380nm-450nm$

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Dont know the first part but melanin quantities change the dkin color

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2 years ago

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