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3 years ago

Which best describes the purpose of a control sample?

1 answer:

maks197457 [2]3 years ago

7 0

A control sample serves as a sample used to eliminate errors or minimize them. Also, it is used to prevent the effect of one parameter which is not the subject being studied. For instance, in an adsorption experiment a control sample is always included wherein in a flask it only contains the adsorbate solution. The said sample is responsible for calculating how much of the adsorbate is being adsorbed on the sides of the flask.

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when 4.73g of solid was heated, the residue weighed 4.10g 320 cubic centimetre of gas( at RTP) was evolved. calculate the molecu

Eddi Din [679]

Answer:

48 g/mol

Explanation:

Step 1: Calculate the mass of the gas (m)

According to the law of conservation of mass, the mass of the solid before the decomposition must be equal to the sum of the masses of the solid residue and the gas

mSolid = mResidue + mGas

mGas = mSolid - mResidue = 4.73 g - 4.10 g = 0.63 g

Step 2: Convert 320 cm³ to L

We will use the conversion factor 1 L = 1000 cm³.

320 cm³ × 1 L/1000 cm³ = 0.320 L

Step 3: Calculate the moles of gas (n)

The gas is at room temperature (298.15 K) and room pressure (1 atm). We can calculate the moles of gas using the ideal gas equation.

P × V = n × R × T

n = P × V/R × T

n = 1 atm × 0.320 L/(0.0821 atm.L/mol.K) × 298.15 K = 0.0131 mol

Step 4: Calculate the molecular mass of the gas (M)

We will use the following expression.

M = m/n = 0.63 g/0.0131 mol = 48 g/mol

8 0

3 years ago

The isotope 90_Sr has a half-life of 28.8 years. What is the activity, measured in atoms/second of a 50 mg sample of "Sr? (10 pt

blsea [12.9K]

Answer:

$2.5523\times 10^{11} atoms/seconds$ is the activity, measured in of a 50 mg sample of 90-Sr.

Explanation:

Half life of the 90-Sr , $t_{1/2}= 28.8 years$

Activity coefficient of the 90-Sr = $\lambda$

$\lambda =\frac{0.693}{28.8 years}=0.0240625 year^{-1}$

Mass of 90-Sr = 50 mg = 0.050 g

Molecular mass of 90-Sr = 90 g/mol

Moles of 90-Sr = $\frac{0.050 g}{90 g/mol}=0.0005555 mol$

Number of atom in 0.0005555 moles of 90-Sr:

$0.0005555 mol\times 6.022\times 10^{23} mol^{-1}=3.3455\times 10^{20} atoms$

$\lambda =0.0240625 year^{-1}=\frac{0.0240625}{3.154\times 10^7 s}=7.6292\times 10^{-10} s^{-1}$

1 year = $3.154\times 10^7 seconds$

Activity measured in atoms per seconds:

= Number of atoms × $\lambda$

$=3.3455\times 10^{20} atoms\times 7.6292\times 10^{-10} s^{-1}$

$=2.5523\times 10^{11} atoms/s$

5 0

3 years ago

An acid has a molarity of 0.01 M. What does the 0.01 M refer to?

bulgar [2K]

Answer : The correct option is, The concentration of the acid.

Explanation :

Molarity : Molarity is defined as the moles of solute present in one liter of the solution. Or it is defined as the concentration of solute present in one liter of solution.

The unit of molarity is, (M) i.e, mole/liter. It is also known as molar concentration.

Molarity of 0.01 M means, 0.01 concentration of the acid present in the solution.

Therefore, the 0.01 M refer to the concentration of the acid.

5 0

4 years ago

Read 2 more answers

What is the filtrate?

kondaur [170]

Answer:

a liquid which has passed through a filter.

Explanation:

Filtration is a physical separation process that separates solid matter and fluid from a mixture using a filter medium that has a complex structure through which only the fluid can pass

5 0

2 years ago

1 Which climate zone has hot summers, cold winters, and average amounts of precipitation throughout the year? (2 points)

NemiM [27]

Answer:

A !!

Explanation:

because the equator is basically all the weather , so it cant be d , c , or b because in the artic is not hot and the desert cant be cold . so the answer is A

6 0

3 years ago

Read 2 more answers