Why is mercury the only metal to have been used in thermometers

Why are most solid ionic compounds electrically nonconductive, whereas aqueous solutions of ionic compounds are good conductors

Allisa [31]

Answer:

there must be free-moving electrons in a compound to conduct electricity.

in solid ionic compounds, there are no free electrons so it can't conduct electricity.

But in aqueous form the forces of attraction are broken and the ions (cations and anions) are free to move. This means there are free electrons that allow the aqueous compound to conduct electricity.

8 0

3 years ago

Iron has a mass of 7.87 g per cubic centimeter of volume, and the mass of an iron atom is 9.27 × 10-26 kg. If you simplify and t

Talja [164]

(a) what is the average volume (in cubic meters) required for each iron atom
For this case, the density of Iron would be 7.87g/cm³

V = 9.27 x 10^-26 kg / 7.87g/cm³ ( 1 kg / 1000 g)
V = 1.18 x 10-23 cm³

(b) what is the distance (in meters) between the centers of adjacent atoms?
We assume the atoms as cube, so we use the volume of the cube to calculate the distance of the atoms.

V = 1.18 x 10-23 cm³ = s³
s = 2.28 x 10^-8 cm

7 0

3 years ago

Read 2 more answers

CS2 (s) + 3 O2 (g) → CO2 (g) + 2 SO2 (g)

Natasha_Volkova [10]

Answer:

2.067 L ≅ 2.07 L.

Explanation:

The balanced equation for the mentioned reaction is:

CS₂(g) + 3O₂(g) → CO₂(g) + 2SO₂(g),

It is clear that 1.0 mole of CS₂ react with 3.0 mole of O₂ to produce 1.0 mole of CO₂ and 2.0 moles of SO₂.

At STP, 3.6 L of H₂ reacts with (?? L) of oxygen gas:

It is known that at STP: every 1.0 mol of any gas occupies 22.4 L.

using cross multiplication:

1.0 mol of O₂ represents → 22.4 L.

??? mol of O₂ represents → 3.1 L.

∴ 3.1 L of O₂ represents = (1.0 mol)(3.1 L)/(22.4 L) = 0.1384 mol.

To find the no. of moles of SO₂ produced from 3.1 liters (0.1384 mol) of hydrogen:

Using cross multiplication:

3.0 mol of O₂ produce → 2.0 mol of SO₂, from stichiometry.

0.1384 mol of O₂ produce → ??? mol of SO₂.

∴ The no. of moles of SO₂ = (2.0 mol)(0.1384 mol)/(3.0 mol) = 0.09227 mol.

Again, using cross multiplication:

1.0 mol of SO₂ represents → 22.4 L, at STP.

0.09227 mol of SO₂ represents → ??? L.

∴ The no. of liters of SO₂ will be produced = (0.09227 mol)(22.4 L)/(1.0 mol) = 2.067 L ≅ 2.07 L.

8 0

3 years ago

The activation energy for proline isomerization of a peptide depends on the identity of the preceding residue and obeys Arrheniu

MAVERICK [17]

Answer:

Activation energy of phenylalanine-proline peptide is 66 kJ/mol.

Explanation:

According to Arrhenius equation- $k=Ae^{\frac{-E_{a}}{RT}}$ , where k is rate constant, A is pre-exponential factor, $E_{a}$ is activation energy, R is gas constant and T is temperature in kelvin scale.

As A is identical for both peptide therefore-

$\frac{k_{ala-pro}}{k_{phe-pro}}=e^\frac{[E_{a}^{phe-pro}-E_{a}^{ala-pro}]}{RT}$

Here $\frac{k_{ala-pro}}{k_{phe-pro}}=\frac{0.05}{0.005}$ , T = 298 K , R = 8.314 J/(mol.K) and $E_{a}^{ala-pro}=60kJ/mol$

So, $\frac{0.05}{0.005}=e^{\frac{[E_{a}^{phe-pro}-(60000J/mol)]}{8.314J.mol^{-1}.K^{-1}\times 298K}}$

$\Rightarrow$ $E_{a}^{phe-pro}=65705J/mol=66kJ/mol$ (rounded off to two significant digit)

So, activation energy of phenylalanine-proline peptide is 66 kJ/mol

7 0

3 years ago

An element's atomic mass does not include the mass of its Electrons Protons Neutrons

klio [65]

Mass of electrons are not included when calculating the atomic mass of element. Atomic mass of the element is equal to proton + neurons. Example the the mass number of Nitrogen can be calculated as 7 protons + 7 neutrons to give 14 . thus nitrogen has a mass number of 14

4 0

3 years ago