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3 years ago

Explain how you know that no new element with an atomic number less than 100 will be discovered

1 answer:

Klio2033 [76]3 years ago

3 0

The elements are identified by its aomic number and they are placed in the periodic table in ascending order of atomic number.

There is one unique element for a given atomic number.

For example, atomic number 1 identifies Hydrogen and there cannot be another different element with the same atomic number.

All the elements with atomic numbers from 1 to 118 have been discovered. So, you know that there is not room for new products with atomic number equal or less than 118.

You might be interested in

n the formation of chloromethane and hydrogen chloride. The overall reaction is 2CH4(g)+3Cl2(g)⟶2CH3Cl(g)+2HCl(g)+2Cl−(g) 2CH4(g

IrinaVladis [17]

Answer:

The total pressure in the flask is 0,619 atm.

Explanation:

For the reaction:

2CH₄(g) + 3Cl₂(g) ⟶ 2 CH₃Cl(g) + 2HCl(g) + 2Cl⁻(g)

The moles of CH₄ in 295 mL at STP are:

n = PV/RT

Where P is pressure (1 atm), V is volume (0,295L), R is gas constant (0,082atmL/molK) and T is temperature (273,15 K)

Replacing, moles of CH₄ are 0,0132 moles

In the same way, moles of chlorine are 0,0324 moles

As 3 moles of Cl₂ react with 2 moles of CH₄, for a total reaction of 0,0132 moles of CH₄ you need:

0,0132 moles CH₄ × $\frac{3 moles Cl_{2}}{2 moles CH_{4}}$ = 0,0198 moles Cl₂. That means that 0,0324-0,0198 = 0,0126 moles of Cl₂ are in excess.

As the reaction reaches in 77%, the moles of CH₄ that don't react are:

0,0132×(100%-77%)= 3,036x10⁻³ moles of CH₄

Also, the moles of Cl₂ that don't react are:

0,0126 + 0,0198×(100%-77%)= 0,0172 moles of Cl₂

The moles produced of each compound are:

0,0132×77% × $\frac{2 moles CH_{3}Cl}{2 moles CH_{4}}$ = 0,0102 moles of CH₃Cl -that are the same moles of HCl and Cl⁻-

Thus, total moles in the flask are:

3,036x10⁻³ moles of CH₄ + 0,0172 moles of Cl₂ + 0,0102 moles of CH₃Cl + 0,0102 moles of HCl + 0,0102 moles of Cl⁻ = 0,0507 total moles

As the volume of the flask is 2,00L and the final temperature is 298 K. The total pressure in the flask is:

P = nRT/V

P = 0,619 atm

I hope it helps!

3 0

3 years ago

The reaction 2CH4(g)⇌C2H2(g)+3H2(g) has an equilibrium constant of K = 0.154. If 6.30 mol of CH4, 4.20 mol of C2H2, and 11.15 mo

boyakko [2]

Answer:

C₂H₂ + 3H₂ ⟶ 2CH₄

Explanation:

The initial concentrations are:

[CH₄] = 6.30 ÷ 6.00 = 1.05 mol·L⁻¹

[C₂H₂] = 4.20 ÷ 6.00 = 0.700 mol·L⁻¹

[H₂] = 11.15 ÷ 6.00 = 1.858 mol·L⁻¹

2CH₄ ⇌ C₂H₂ + 3H₂

I/mol·L⁻¹: 1.05 0.700 1.858

$Q = \dfrac{\text{[C$_{2}$H$_{2}$][H$_{2}$]}^{3}}{\text{[CH$_{4}$]}^{2}} = \dfrac{ 0.700\times 1.858^{3}}{1.05^{2}}= 4.07$

Q > K

That means we have too many products.

The reaction will go to the left to get rid of the excess products.

C₂H₂ + 3H₂ ⟶ 2CH₄

8 0

4 years ago

6. How many moles of water would require 92.048 kJ of heat to raise its temperature from 34.0 °C to 100.0 °C? (3 marks)

scoray [572]

Taking into account the definition of calorimetry, 0.0185 moles of water are required.

<h3>Calorimetry</h3>

Calorimetry is the measurement and calculation of the amounts of heat exchanged by a body or a system.

Sensible heat is defined as the amount of heat that a body absorbs or releases without any changes in its physical state (phase change).

So, the equation that allows to calculate heat exchanges is:

Q = c× m× ΔT

where Q is the heat exchanged by a body of mass m, made up of a specific heat substance c and where ΔT is the temperature variation.

<h3>Mass of water required</h3>

In this case, you know:

Heat= 92.048 kJ
Mass of water = ?
Initial temperature of water= 34 ºC
Final temperature of water= 100 ºC
Specific heat of water = 4.186 $\frac{J}{gC}$

Replacing in the expression to calculate heat exchanges:

92.048 kJ = 4.186 $\frac{J}{gC}$ × m× (100 °C -34 °C)

92.048 kJ = 4.186 $\frac{J}{gC}$ × m× 66 °C

m= 92.048 kJ ÷ (4.186 $\frac{J}{gC}$ × 66 °C)

m= 0.333 grams

<h3>Moles of water required</h3>

Being the molar mass of water 18 $\frac{g}{mole}$ , that is, the amount of mass that a substance contains in one mole, the moles of water required can be calculated as:

$amount of moles=0.333 gramsx\frac{1 mole}{18 grams}$

amount of moles= 0.0185 moles

Finally, 0.0185 moles of water are required.

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8 0

3 years ago

What are substance made of

Stella [2.4K]

Answer:

Lesson Summary. A substance is simply a pure form of matter. In other words, a substance is matter than contains only one type of atom or molecule. Pure substances can be further divided into two sub-categories: elements and compounds.

Explanation:

Radhe Radhe❤

4 0

3 years ago

Answer them please i cant figure out what it is

miss Akunina [59]

Answer:

iv. The motion between A & B moves at a further distance than C & D's

v. The cyclist travels 800 meters

vi. It takes approx. 80 seconds

vii. The cyclist's speed is 10 meters per second (m/s)

viii. The cyclist's speed is also 10 meters per second (m/s)

vii. (2) The cyclist's average speed is 10 meters per second (m/s)

Explanation:

Speed is calculated using the formula distance divided by time (d/t)

vii (2) needs further explanation:

Though there is a moment of rest, the cyclist still travels the same speed throughout the entire trip. To check this answer however, you can total the distance and time the cyclist traveled and use speed formula to get 10 meters per second, again.

6 0

3 years ago