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3 years ago

Which statement is true about molarity and percent by mass? (3 points)

Chemistry

2 answers:

lakkis [162]3 years ago

5 0

Answer: The correct option is, They are different units of concentration.

Explanation: Molarity : It is defined as the number of moles of solute present in one liter of solution.

Usimov [2.4K]3 years ago

3 0

Answer: They ate different units of concentration

Explanation: I took the test

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Atomic absorption spectroscopy was used to determine the amount of aluminum in a sample of sunscreen. A blank solution was measu

Pepsi [2]

Answer:

LOD = 0,0177

LOQ = 0,0345

Explanation:

Detection limit (LOD) is defined as the lowest signal which, with a stated probability, can be distinguished from a suitable blank signal. In the same way, quantification limit (LOQ) is defined as the lowest analyte concentration that can be quantitatively detected with a stated accuracy and precision.

There are many formulas but the most used are:

LOD = X + 3σ

LOQ = X + 10σ

Where X is average and σ is standard desvation

For the blanks readings the average X is 0,0105 and σ is 0,0024

Thus:

LOD = 0,0177

LOQ = 0,0345

I hope it helps!

3 0

3 years ago

Calculate the bond energy per mole for breaking all the bonds in methane, CH4. Express your answer to four significant figures a

lesantik [10]

The energy that is essential to break one C-H bond is 414 kJ/mol. Since, there are four C-H bonds in CH4, the energy Δ HCH4 for breaking all the bonds is calculated as Δ HCH4 = 4 x bond energy of C-H bond. By multiplying the 4 with the 414 kJ/mol you can get the answer of 1656 kJ/mol CH4 molecules.

4 0

3 years ago

Read 2 more answers

Analysis of a gaseous chlorofluorocarbon, CClxFy, shows that it contains 11.79% C and 69.57% Cl. In another experiment, you find

uranmaximum [27]

Answer:

The molecular formula = $C_2Cl_{4}F_2$

Explanation:

$Moles =\frac {Given\ mass}{Molar\ mass}$

% of C = 11.79

Molar mass of C = 12.0107 g/mol

% moles of C = 11.79 / 12.0107 = 0.9816

% of Cl = 69.57

Molar mass of Cl = 35.453 g/mol

% moles of Cl = 69.57 / 35.453 = 1.9623

Given that the gaseous chlorofluorocarbon only contains chlorine, flourine and carbon. So,

% of F = 100% - % of C - % of C = 100 - 11.79 - 69.57 = 18.64

Molar mass of F = 18.998 g/mol

% moles of F = 18.64 / 18.998 = 0.9812

Taking the simplest ratio for C, Cl and F as:

0.9816 : 1.9623 : 0.9812

= 1 : 2 : 1

The empirical formula is = $CCl_2F$

Also, Given that:

Pressure = 21.3 mm Hg

Also, P (mm Hg) = P (atm) / 760

Pressure = 21.3 / 760 = 0.02803 atm

Temperature = 25 °C

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15

So,

T = (25 + 273.15) K = 298.15 K

Volume = 458 mL = 0.458 L (1 mL = 0.001 L)

Using ideal gas equation as:

PV=nRT

where,

P is the pressure

V is the volume

n is the number of moles

T is the temperature

R is Gas constant having value = 0.0821 L.atm/K.mol

Applying the equation as:

0.02803 atm × 0.458 L = n × 0.0821 L.atm/K.mol × 298.15 K

⇒n = 0.00052445 moles

Given that :

Amount = 0.107 g

Molar mass = ?

The formula for the calculation of moles is shown below:

$moles = \frac{Mass\ taken}{Molar\ mass}$

Thus,

$0.00052445= \frac{0.107\ g}{Molar\ mass}$

$Molar\ mass= 204.0233\ g/mol$

Molecular formulas is the actual number of atoms of each element in the compound while empirical formulas is the simplest or reduced ratio of the elements in the compound.

Thus,

Molecular mass = n × Empirical mass

Where, n is any positive number from 1, 2, 3...

Mass from the Empirical formula = 1×12.0107 + 2×35.453 + 1×18.998 = 101.9147 g/mol

Molar mass = 204.0233 g/mol

So,

Molecular mass = n × Empirical mass

204.0233 = n × 101.9147

⇒ n = 2

The molecular formula = $C_2Cl_{4}F_2$

6 0

3 years ago

What volume of a 0.550 M solution of potassium hydroxide (KOH) can be made with 19.9 g of potassium hydroxide?

Natalija [7]

Answer:

0.645 L

Explanation:

To find the volume, you need to (1) convert grams to moles (using the molar mass) and then (2) calculate the volume (using the molarity ratio). The final answer should have 3 sig figs to match the sig figs of the given values.

(Step 1)

Molar Mass (KOH): 39.098 g/mol + 15.998 g/mol + 1.008 g/mol

Molar Mass (KOH): 56.104 g/mol

19.9 grams KOH 1 mole
-------------------------- x ----------------------- = 0.355 moles KOH
56.014 grams

(Step 2)

Molarity = moles / volume <----- Molarity ratio

0.550 M = 0.355 moles / volume <----- Insert values

(0.550 M) x volume = 0.355 moles <----- Multiply both sides by volume

volume = 0.645 L <----- Divide both sides by 0.550

6 0

1 year ago

What information is presented inside each square of the periodic table?

Verdich [7]

The symbol, the atomic mass, the number of protons and electrons

8 0

3 years ago