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2 years ago

Why must the spectrophotometer cell be removed from the instrument between readings?

1 answer:

5 0

Spectrophotometric cell or a cuvette is made of quartz for UV spectrophotometers. These cuvettes are used as sample holders for the spectrophotometric determination of the analytes. The material that makes up the cuvette and the condition of the cuvette is to be taken care of in order to avoid erroneous absorbance readings. The sample holder or the cuvette must be removed from the spectrophotometer in between two successive readings. This is to ensure that the light sensing detector of the instrument is not affected.

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Someone help please , I’ll give brain . Question 10 !

Rudik [331]

Answer:it’s c

Explanation:

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4 0

2 years ago

4. Calculate the final concentration if water is added to 1.5 L of a 12 M

konstantin123 [22]

Answer:

Explanation:

(Molarity x Volume)concentrated soln = (Molarity x Volume)diluted doln

Molarity dilute soln = [(M x V)conc/V (dilute)] = 1.5L x 12M / 3.0L = 6M final dilute soln

6 0

3 years ago

A 720. cm^3 vessel contains a mixture of Ar and Xe. If the mass of the gas mixture is 2.966 g at 25.0°C and the pressure is 760.

sleet_krkn [62]

Explanation:

The given data is as follows.

Pressure (P) = 760 torr = 1 atm

Volume (V) = $720 cm^{3}$ = 0.720 L

Temperature (T) = $25^{o}C$ = (25 + 273) K = 298 K

Using ideal gas equation, we will calculate the number of moles as follows.

PV = nRT

Total atoms present (n) = $\frac{PV}{RT}$

= $1 \times \frac{0.720 L}{0.0821 \times 298}$

= 0.0294 mol

Let us assume that there are x mol of Ar and y mol of Xe.

Hence, total number of moles will be as follows.

x + y = 0.0294

Also, 40x + 131y = 2.966

x = 0.0097 mol

y = (0.0294 - 0.0097)

= 0.0197 mol

Therefore, mole fraction will be calculated as follows.

Mol fraction of Xe = $\frac{y}{(x+y)}$

= $\frac{0.0197}{0.0294}$

= 0.67

Therefore, the mole fraction of Xe is 0.67.

6 0

2 years ago

How much heat in joules is required to heat a 43g sample of aluminum from an initial temperature of 72˚F to a final temperature

Stels [109]

The first step to answering this item is to convert the given temperatures in °F to °C through the equation,

°C = (°F - 32)(5/9)

initial temperature: 72°F

  °C = (72 - 32)(5/9) = 22.22°C

final temperature: 145°F

  °C = (145 - 32)(5/9) = 62.78°C

Substituting to the equation,

H = mcpdT

H = (43 g)(0.903 J/g°C)(62.78 - 22.22)

H = 1574.82 J

<em>Answer: 1574.82 J</em>

3 0

3 years ago

Rhenium (Re) is made up of 37.4% 185Re and 62.6% 187Re. The atomic mass of 185Re is 184.953 amu. The atomic mass of 187Re is 186

Anna007 [38]

To calculate the average mass of the element, we take the summation of the product of the isotope and the percent abundance. We calculate as follows:

Average atomic mass = .374 ( 184.953 amu ) + .626 ( <span>186.958 amu ) = 186.208 amu

Hope this answers the question. Have a nice day.</span>

8 0

2 years ago

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