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3 years ago

B. Why is this number called a "mass” number?

Chemistry

1 answer:

deff fn [24]3 years ago

7 0

Answer:

The mass of the atom depends on the sub atomic particles present in the nucleus of an atom.

That is, the protons and the neutrons.

Electrons are present around the nucleus and the mass is negligible since its mass is very very less.

mass of a proton = $1.673\times10^{-27} kg$

mass of a neutron = $1.675 \times 10^{-27} kg$

mass of an electron = $9.109 \times 10^{-31} kg$

Mass number represents the mass of one particular isotope and it is a whole number for example, $_6 C^{13}$

Mass number is 13 and atomic number is 6 for the carbon isotope C-13.

Atomic mass is different from mass number and it is a fraction since it is the average atomic mass of all the isotopes of an atom.

Atomic mass of C is 12.011 amu which we see in the periodic table is the average atomic mass of isotopes C-12, C-13 and C-14.

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TIME REMAINING

vladimir1956 [14]

Answer:

The pressure of the gas will "increases by a factor of four."

Explanation:

The absolute zero in other words called as the absolute temperature. Whereas the absolute zero is the least possible temperature. In which nothing will remain cold and no heat can be released or present in the substance. When it is described in the figure it will be, –273.15 degrees Celsius on the Celsius scale. and 0 K on the Kelvin scale. This absolute temperature concept has been raised from the third law of the thermodynamics.

6 0

3 years ago

Part iv. Is the neutralization reaction enthalpy favored?

Burka [1]

Yes, it is a special case of enthalpy of neutralization.

The enthalpy of neutralization (ΔHn) is the change in enthalpy that occurs when one equivalent of an acid and one equivalent of a base undergo a neutralization reaction to form water and a salt.

The standard enthalpy change of neutralization is the enthalpy change when solutions of an acid and an alkali react together under standard conditions to produce 1 mole of water.

5 0

3 years ago

What is the mole, and why is it useful in chemistry?

Snowcat [4.5K]

Answer:The mole is important because it allows chemists to work with the subatomic world with macro world units and amounts. Atoms, molecules and formula units are very small and very difficult to work with usually. However, the mole allows a chemist to work with amounts large enough to use.

Explanation:

6 0

3 years ago

son4ous [18]

Answer: The molar enthalpy change is 73.04 kJ/mol

Explanation:

$HCl+NaOH\rightarrow NaCl+H_2O$

moles of HCl= $molarity\times {\text {vol in L}}=0.415mol/L\times 0.1=0.0415mol$

As NaOH is in excess 0.0415 moles of HCl reacts with 0.0415 moles of NaOH.

volume of water = 100.0 ml + 50.0 ml = 150.0 ml

density of water = 1.0 g/ml

mass of water = $volume \times density=150.0ml\times 1.0g/ml=150.0g$

$q=m\times c\times \Delta T$

q = heat released

m = mass = 150.0 g

c = specific heat = $4.184J/g^0C$

$\Delta T$ = change in temperature = $4.83^0C$

$q=150.0\times 4.184\times 4.83$

$q=3031.3J$

Thus 0.0415 mol of HCl produces heat = 3031.3 J

1 mol of HCL produces heat = $\frac{3031.3}{0.0415}\times 1=73043.3J=73.04kJ$

Thus molar enthalpy change is 73.04 kJ/mol

8 0

3 years ago

A dilute solution is prepared by transferring 40.00 ml of a 0.3433 m stock solution to a 750.0 ml volumetric flask and diluting

alina1380 [7]

We are given with the initial volume of the substance and the molarity. The first thing that needs to be done is to multiply the equation in order to obtain the number of moles such as shown below.

number of moles = (40 mL) x (1 L / 1000 mL) x (0.3433 moles / L)
number of moles = 0.013732 moles

To get the value of the molarity of the diluted solution, we divide the number of moles by the total volume.
molarity = (0.013732 moles) / (750 mL / 1000 mL/L) = 0.0183 M

Similarly, we can solve for the molarity by using the equation,
M₁V₁ = M₂V₂
Substituting the known values in the equation,
(0.3433 M)(40 mL) = M₂(750 mL)
M₂ = 0.0183 M

5 0

3 years ago