All categories

3 years ago

Find the mass of sucrose (molecular mass=342) required to be dissolved per 600cm² solution to prepare a semi molar solution.

Chemistry

1 answer:

Natalka [10]3 years ago

4 0

Answer:

102.6 g

Explanation:

Firstly, let's understand the terms used in the question. Semi-molar solution is a solution which has a molarity of:

$c=\frac{1}{2} M=0.5 M$

We're given the molar mass of:

$M=342 \frac{g}{mol}$

Let's use the definition of molarity: molarity is the ratio between the moles of solute and the volume of solution:

$c=\frac{n}{V}$

From here, we wish to express moles, n, as the ratio of mass of sucrose to its molar mass:

$n=\frac{m}{M}$

Substitute it back into the equation of molarity:

$c=\frac{n}{V}=\frac{\frac{m}{M} }{V}=\frac{m}{MV}$

Since we wish to find mass, let's multiply both sides of the equation by MV to obtain mass equation:

$m=cMV$

Now, convert volume into liters knowing that 1 mL = 1 cm³ and 1000 mL = 1 L:

$600 cm^3 \cdot\frac{1 mL}{1 cm^3} \cdot \frac{1 L}{1000 mL} =0.600 L$

Substitute all three variables into the equation:

$m=0.5 M\cdot342 \frac{g}{mol}\cdot0.600 L=102.6 g$

You might be interested in

Atoms with the same number of protons but different number of neutrons are called.......

Len [333]

I gotchuuuuu it’s Isotopes

8 0

3 years ago

A) Combustion analysis of toluene, a common organic solvent, gives 5.86 mg of CO2 and 1.37 mg of H2O. If the compound contains o

Mumz [18]

Answer:

For a: The empirical formula for the given compound is $CH$

For b: The empirical and molecular formula for the given organic compound are $C_{10}H_{20}O$

Explanation:

For a:

The chemical equation for the combustion of hydrocarbon follows:

$C_xH_y+O_2\rightarrow CO_2+H_2O$

where, 'x', and 'y' are the subscripts of Carbon and hydrogen respectively.

We are given:

Conversion factor used: 1 g = 1000 mg

Mass of $CO_2=5.86mg=5.86\times 10^{-3}g$

Mass of $H_2O=1.37mg=1.37\times 10^{-3}g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in $5.86\times 10^{-3}g$ of carbon dioxide, $\frac{12}{44}\times 5.86\times 10^{-3}=1.60\times 10^{-3}g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in $1.37\times 10^{-3}g$ of water, $\frac{2}{18}\times 1.37\times 10^{-3}=0.152\times 10^{-3}g$ of hydrogen will be contained.

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{1.60\times 10^{-3}g}{12g/mole}=0.133\times 10^{-3}moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.152\times 10^{-3}g}{1g/mole}=0.152\times 10^{-3}moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is $0.133\times 10^{-3}$ moles.

For Carbon = $\frac{0.133\times 10^{-3}}{0.133\times 10^{-3}}=1$

For Hydrogen = $\frac{0.152\times 10^{-3}}{0.133\times 10^{-3}}=1.14\approx 1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H = 1 : 1

Hence, the empirical formula for the given compound is $CH$

For b:

The chemical equation for the combustion of menthol follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of Carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2$ = 0.2829 g

Mass of $H_2O$ = 0.1159 g

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44g of carbon dioxide, 12 g of carbon is contained.

So, in 0.2829 g of carbon dioxide, $\frac{12}{44}\times 0.2829=0.077g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18g of water, 2 g of hydrogen is contained.

So, in 0.1159 g of water, $\frac{2}{18}\times 0.1159=0.013g$ of hydrogen will be contained.

Mass of oxygen in the compound = (0.1005) - (0.077 + 0.013) = 0.105 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{0.077g}{12g/mole}=0.0064moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{0.013g}{1g/mole}=0.013moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{0.0105g}{16g/mole}=0.00065moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.00065 moles.

For Carbon = $\frac{0.0064}{0.00065}=9.84\approx 10$

For Hydrogen = $\frac{0.013}{0.00065}=20$

For Oxygen = $\frac{0.00065}{0.00065}=1$

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 10 : 20 : 1

The empirical formula for the given compound is $C_{10}H_{20}O$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

$n=\frac{\text{Molecular mass}}{\text{Empirical mass}}$

We are given:

Mass of molecular formula = 156 g/mol

Mass of empirical formula = 156 g/mol

Putting values in above equation, we get:

$n=\frac{156g/mol}{156g/mol}=1$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(1\times 10)}H_{(1\times 20)}O_{(1\times 1)}=C_{10}H_{20}O$

Hence, the empirical and molecular formula for the given organic compound are $C_{10}H_{20}O$

3 0

3 years ago

Why is Sodium chloride a compound but not a molecule? I thought all the compounds are molecule but not all molecules are compoun

Firdavs [7]

Molecule is the general term used to describe any atoms that are connected by chemical bonds. Every combination of atoms is a molecule. A compound is a molecule made of atoms from different elements.
Well, if a molecule is considered to be a discrete small unit made up of atoms joined together, then NaCl, and any other ionic solid is not really a molecule. In NaCl we have a repetitive crystal structure in which each Na+ ion is surrounded by Cl- ions, and vice-versa, for as far as the crystal extends. There really isn't such a thing as an NaCl molecule.

8 0

3 years ago

An electron has an uncertainty in its position of 513 pm. What is the uncertainty in its velocity?

ella [17]

"The uncertainty in velocity is Δv=1.05⋅105m/s . According to the Heisenberg Uncertainty Principle, you cannot measure simultaneously with great precision both the momentum and the position of a particle. m - the mass of an electron - 9.10938⋅10−31kg."
-socratic.com

7 0

4 years ago

If an isotope has 85 protons, 110 neutrons, and 85 electrons, it has a mass number of what?

telo118 [61]

Answer:

Mass number = 195

Explanation:

Isotope:

An atom of an element that contain same atomic number but different atomic mass.

The difference in atomic mass is due to the different number of neutrons present, but the number protons and electrons are remain same.

In given isotope of an atom there are 85 protons and 85 electrons while number of neutrons are 110.

The number of electron or number of protons are called atomic number while mass number of an atom is sum of protons and neutrons. The umber of protons and electrons are always equal to make the atom electrically neutral and when an atom loses its valance electron the number of protons increases and thus positive charge increased and atom form cation.

Mass number = number of protons + number of neutrons

Mass number = 85 + 110 = 195

7 0

3 years ago