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Anit [1.1K]
3 years ago
15

Luca wants to identify and quantity the chemicals causing air pollution in a city, but he is using a manual air sampler to colle

t air sample.
Why should he update his current sampler to an electronic one?
Chemistry
1 answer:
xenn [34]3 years ago
5 0

Answer

Manual samplers are prone to effects of temperature, speed of wind and air concentrations.

Explanation

Manual samplers face several challenges that can act as drawbacks to obtaining accurate results. They are subjected to effects of sampling duration where long sampling times are needed to obtain adequate mass for detection. Manual samplers face challenges when measuring non-volatile species because particles are observed into the adsorption medium at a slower rate of diffusion.

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A solution of water (kf=1.86 ∘c/m) and glucose freezes at − 2.15 ∘c. what is the molal concentration of glucose in this solution
Reil [10]
<span>1.16 moles/liter The equation for freezing point depression in an ideal solution is ΔTF = KF * b * i where ΔTF = depression in freezing point, defined as TF (pure) â’ TF (solution). So in this case ΔTF = 2.15 KF = cryoscopic constant of the solvent (given as 1.86 âc/m) b = molality of solute i = van 't Hoff factor (number of ions of solute produced per molecule of solute). For glucose, that will be 1. Solving for b, we get ΔTF = KF * b * i ΔTF/KF = b * i ΔTF/(KF*i) = b And substuting known values. ΔTF/(KF*i) = b 2.15âc/(1.86âc/m * 1) = b 2.15/(1.86 1/m) = b 1.155913978 m = b So the molarity of the solution is 1.16 moles/liter to 3 significant figures.</span>
7 0
3 years ago
During the titration of a diluted vinegar sample with a sodium hydroxide solution, the volume of sodium hydroxide used was less
lapo4ka [179]

Answer:

B and D could be true

Explanation:

A volume of sodium hydroxide less than expected could occurs for two reasons:

The real concentration of sodium hydroxide was higher than expected or the amount of vinegar added was less than expected:

A. The sodium hydroxide solution had been allowed to stand exposed to the air for a long time prior to the titration.  FALSE. A long expose  to the air decreases concentration of the NaOH.

B. The volumetric flask used to prepare the diluted vinegar solution was rinsed with water prior to use.  TRUE. You add a less amount of vinegar doing you require less amount of NaOH than expected.

C. The burette used to deliver the sodium hydroxide solution was rinsed with water prior to use.  FALSE. Thus, you add a less amount of NaOH than expected. To explain the matter, you add more NaOH than expected.

D. The pipette used to deliver the vinegar solution was rinsed with water prior to use. TRUE. Again, you are adding a less amount of Vinegar than expected doing the necessary NaOH during titration less than expected

6 0
3 years ago
Jamie is measuring the mass of one mole of carbon. She measures the mass 4 times, achieving the following measurements: 11.86 g,
azamat

This is an incomplete question, here is a complete question.

Distinguish between Accuracy and Precision Question Jamie is measuring the mass of one mole of carbon. She measures the mass 4 times, achieving the following measurements: 11.86 g, 11.87 g, 11.89 g, and 11.90 g. If the accepted value of one mole of carbon is 12.11 g, how can Jamie's measurements best be described?

Select the correct answer below:

Jamie's measurements are both precise and accurate,

Jamie's measurements are accurate but not precise.

Jamie's measurements are precise but not accurate,

Jamie's measurements are neither precise nor accurate,

Answer : The correct option is, Jamie's measurements are precise but not accurate.

Explanation :

Accuracy : It is defined as the closeness of a measured value to a standard or known value.

For Example: If the mass of a substance is 50 kg and one person weighed 48 kg and another person weighed 55 kg. Then, the weight measured by first person is more accurate.

Precision : It is defined as the closeness of two or more measurements to each other.

For Example: If you weigh a given substance five times and you get 1.8 kg each time. Then the measurement is said to be precise.

Level of precision is determined by the maximum number of decimal places.

As we are given that:

The measurements are, 11.86, 11.87, 11.89 and 11.90

The accepted value is, 12.11

The average of these values =  \frac{11.86+11.87+11.89+11.90}{4}=11.88

From this we conclude that, these measurements are close to each other that means they are precise. But the accepted value are not equal to average of four values that means they are not accurate.

Hence, the correct option is, Jamie's measurements are precise but not accurate.

7 0
3 years ago
A compound formed from titanium and oxygen has the formula TiO2. Which of the following is true about the ratio of number Ti and
Finger [1]

Answer:

2

Explanation:

There are some basic laws that guide the combination of elements chemically. These are the law of conservation of mass, law of definite proportion, law of multiple proportion and the law of reciprocal proportion.

For this question, the useful law to use is the law of definite proportion. Here, it is stated that no matter the method of preparation or source of preparation, the elements of a chemical compound are always present in a fixed ratio.

What this means that at any point in time, the compound titanium dioxide contains one atom of titanium and two atoms of oxygen. This means that both atoms are present at all times in a proportion of 1 to 2 .

4 0
3 years ago
Why is Cellular Respiration so important?
Nesterboy [21]
I say it’s A. Hopefully
5 0
3 years ago
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