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3 years ago

Which of the following are covalent compounds? Select all that apply. CaO CO2 KBr NO

Chemistry

1 answer:

Sergeeva-Olga [200]3 years ago

3 0

Answer

CO2 and NO are covalent

Explanation:

Which of the following are covalent compounds? Select all that apply.

CaO

CO2

KBr

the atoms ib covalent compounds share electron pairsO

CaO and KBr are ioinic

CO2 and NO are covalent

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Name the person who developed a table of elements which revealed

aivan3 [116]

Dimitry Mendeleef

Explanation:

Dimitry Mendeleef developed a table of elements which revealed regularities in elemental properties. He discovered the periodic arrangement of elements in 1869 while playing his game of solitaire.

John Newlands in in 1863 proposed the idea of a repeating octaves of properties of elements.
Dimitry Mendeleef described the periodic table or chart in 1869
The chart was based on the periodic law which states that "chemical properties of elements are a periodic function of their atomic weights".
In his periodic table, elements were arranged by atomic weights with recurring properties in a periodic manner>

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Periodic table brainly.com/question/8543126

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3 years ago

Pulverized coal pellets, which may be approximated as carbon spheres of radius ro= 1 mm, are burned in a pure oxygen atmosphere

Ganezh [65]

Answer:

Explanation:

SO; If we assume that:

P should be the diffusion of oxygen towards the surface ; &

Q should be the diffusion of carbondioxide away from the surface.

Then the total molar flux of oxygen is illustrated by :

$Na,x = - cD_{PQ}\frac{dy_P}{dr} +y_P(NP,x + N_Q,x)$

where;

r is the radial distance from the center of the carbon particle.

Since ;

$N_P,x = - N_Q, x$ ; we have:

$Na,x = - cD_{PQ}\frac{dy_P}{dr}$

The system is not steady state and the molar flux is not independent of r because the area of mass transfer $4\pi r^{2}$ is not a constant term.

Therefore, using quasi steady state assumption, the mass transfer rate $4\pi r^{2}N_{P,x}$ is assumed to be independent of r at any instant of time.

$W_{P}=4\pi r^{2}N_{P,x}$

$W_{P}=-4\pi r^{2}cD_{PQ}\frac{dy_{P}}{dr}$

= constant

The oxygen concentration at the surface of the coal particle $yP,R$ will be calculated from the reaction at the surface.

The mole fraction of oxygen at a location far from pellet is 1.

Thus, separating the variables and integrating result into the following:

$W_{P}\int_{R}^{\infty} \frac{dr}{r^{2}}=-4\pi$

$r^{2}cD_{PQ}\int_{y_{P,R}}^{y_{P,\infty }}dy_{P}$

$-W_{P}\frac{1}{r}\mid ^{\infty }_{R}= -4\pi cD_{PQ}(y_{P,\infty }-y_{P,R})$

$=> W_{P}= - 4\pi cD_{PQ}(1-y_{P,R})R$

The mole of oxygen arrived at the carbon surface is equal to the mole of oxygen consumed by the chemical reaction.

$W_{P} = 4 \pi R^2R"$

$W_{P}= 4\pi R^{2}k_{1}"C_{O_{2}}\mid _{R}$

$W_{P}= 4\pi R^{2}k_{1}"c y _{P,R}$

$-4\pi cD_{PQ}(1-y_{P,R})R= - 4\pi R^{2}k_{1}"c y _{P,R}$

$y_{P,R}=\frac{D_{PQ}}{D_{PQ}+Rk_{1}}$

$y_{P,R}=\frac{1.7 \times 10^{-4}}{1.7\times 10^{-4}+10^{-3}\times 0.1}$

$\mathbf{= 0.631}$

Obtaining the total gas concentration from the ideal gas law; we have the following:

where;

R= $0.082m^3atm/kmolK$

$c=\frac{P}{RT} \\ \\ c=\frac{1}{0.082\times 1450} \\ \\ = 0.008405kmol/m^3$

The steady state $O_2$ molar consumption rate is:

$W_{P}= -4\pi cD_{PQ}(1-y_{P,R})R$

$W_{P}= -4\pi (0.008405)(1.7\times 10^{-4})(1-0.631)(10^{-3})$

$W_{P}= - 6.66\times 10^{-9}kmol/s$

5 0

3 years ago

Using the following thermochemical equation, determine the amount of heat produced from the combustion of 24.3 g benzene (C6H6).

Anna007 [38]

Answer:

ΔH = -976.5 kJ

Explanation:

For the reaction given, there are 2 moles of benzene (C6H6). The heat of this reaction is -6278 kJ, which means that the combustion of 2 moles of benzene will lose 6278 kJ of heat. It is an exothermic reaction.

The value of ΔH, the enthalpy, is a way of measurement of the heat, and it depends on the quantity of the matter (number of moles).

So, 24.3 g of benzene has :

n = mass/ molar mass

n = 24.3/78.11

n = 0.311 moles

2 moles ------------ -6278 kJ

0.311 moles ----------- x

By a simple direct three rule:

2x = -1953.08

x = -976.5 kJ

3 0

3 years ago

What is the oxidation number of C in NaHCO3?

Phoenix [80]

Na = +1
H = +1
O = -2
Total charge is 0:
1 + 1 + C + 3 x -2 = 0
C = 4

4 0

3 years ago

A sample of gas in a closed container at a temperature of 100oC and 3 atm is heated to 300oC. What is the pressure of the gas at

Goshia [24]

Answer:

6.14 atm

Explanation:

Initial temperature (T₁) = 100 °C

Initial pressure (P₁) = 4 atm

Final temperature (T₂) = 300 °C

Final pressure (P₂) =?

NOTE: Volume = constant (since the system is a closed system)

Next, we shall convert celsius temperature to Kelvin temperature. This can be obtained as follow:

T(K) = T(°C) + 273

Initial temperature (T₁) = 100 °C

Initial temperature (T₁) = 100 °C + 273 = 373 K

Final temperature (T₂) = 300 °C

Final temperature (T₂) = 300 °C + 273 = 573 K

Finally, we shall determine the pressure at the highest temperature as follow:

Initial temperature (T₁) = 373 K

Initial pressure (P₁) = 4 atm

Final temperature (T₂) = 573 K

Final pressure (P₂) =?

P₁ / T₁ = P₂ / T₂

4 / 373 = P₂ / 573

Cross multiply

373 × P₂ = 4 × 573

373 × P₂ = 2292

Divide both side by 373

P₂ = 2292 / 373

P₂ = 6.14 atm

Thus, the pressure at the highest temperature is 6.14 atm

6 0

3 years ago