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lyudmila [28]
3 years ago
10

What is a rule for determining the mass number of an atom or ion?

Chemistry
1 answer:
Semenov [28]3 years ago
7 0

Answer:

The mass number of the atom is equal to the sum of the number of protons and neutrons in the nucleus

Explanation:

Each proton and each neutron weigh one amu( atomic mass unit), adding together the neutrons and protons and multiplying by 1 amu you get the mass of an atom

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Does anyone know this ?Please I need help
Marrrta [24]

Explanation:

Entropy refers to the degree of disorderliness of system. Basically it refers to how random a system is.

Gong through the options.

A. The phase change is from solid to liquid. Liquid has a greater degree of disorderliness compared to solid hence entropy is increasing.

B. The phase change is from solid to gas. Gas particles has a greater degree of disorderliness compared to solid hence entropy is increasing.

C. The phase change is from aqueous to liquid. Aqueous solutions has a greater degree of disorderliness compared to liquid hence entropy is decreasing.

D. The reactant side has; solid + gas. In the product side, there is only gas. The product side has a greater degree of disorderliness hence the entropy is increasing.

E. The entropy of the product is greater than the entropy of the reactants hence entropy is increasing.

F.  The phase change is from aqueous to solid. Aqueous solutions has a greater degree of disorderliness compared to solid hence entropy is decreasing.

8 0
3 years ago
The number of atoms present in 2.5 mole of triatomic gas is equivalent to ​
RUDIKE [14]

Answer: 1.41725 X 10^{24} atoms

Explanation:

One male of any gas containing no. of atoms$=6.023\times10^{23}$

2.5 moles of gas containing no. of atoms$=2.5\times6.023\times10^{23}$$=15.0575\times10^{23}$

The given gas is triatomic gas. Hence

No. of atoms$=3\times15.075\times10^{23}$

$=14.1725\times10^{23}$\\$=1.41725\times10^{24}$

6 0
3 years ago
The observed rotation of 2.0 gg of a compound in 50 mLmL of solution in a polarimeter tube 25-cmcm long is +47.2 ∘∘ . What is th
Anastaziya [24]

Answer:

[∝] = +472

Explanation:

Specific rotation in a solution is defined as:

[∝] = ∝ / c×l

Where:

[∝] is specific rotation, ∝ is observed rotation (In degrees), c is concentration in g/mL and l is path length (In dm).

∝: +47.2°

c: 2.0g / 50mL = 0.04g/mL

l: 25cm × (1dm /10cm) = 2.5dm

Replacing:

[∝] = +47.2° / 0.04g/mL×2.5dm = <em>+472</em>

I hope it helps!

4 0
3 years ago
What mass of carbon dioxide gas occupies a volume of 81.3L at 204 kPa and a temperature of 95.0°C?
alexandr1967 [171]

Answer:

236.9g

Explanation:

Given parameters:

Volume of gas  = 81.3L

Pressure of gas = 204kPa

temperature of gas = 95°C

Unknown:

Mass of carbondioxide gas = ?

Solution:

To solve this problem, the ideal gas law will be well suited. The ideal gas law is a fusion of Boyle's law, Charles's law and Avogadro's law.

Mathematically, it is expressed as;

                    PV = nRT

the unknown here is n which is the number of moles;

P is the pressure, V is the volume, R is the gas constant and T is the temperature.

convert pressure into atm

               101.325KPa  = 1atm

             204 kPa = \frac{204}{101.325}   = 2atm

Convert temperature to Kelvin;   95 + 273  = 368K

       2 x 81.3 = n x 0.082 x 368

             n = \frac{2 x 81.3}{0.082 x 368}   = 5.38moles

Since the unknown is mass;

 Mass  = number of moles x molar mass

      Molar mass of carbon dioxide  = 12 + 2(16)  = 44g/mol

 Mass  = 5.38 x 44  = 236.9g

5 0
3 years ago
What is the molarity of 122.5 g of AlCl3 in 1.0 L of solution? (MM = 133 g/mol)
yawa3891 [41]
Answer: Molarity is defined as moles of solute per liter of solution. So, find the moles of solute and divide by the liters of solution.
molar mass AlCl3 = 133g/mole
moles AlCl3 = 127 g x 1 mole/133 g = 0.955 moles
liters of solution = 400 ml x 1 liter/1000 ml = 0.400 liters
Molarity = 0.955 moles/0.400 liters = 2.39 M
Explain: I looked it up on wyzant.com
4 0
3 years ago
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