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3 years ago

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Chemistry

1 answer:

Jet001 [13]3 years ago

6 0

Answer:

Explanation:

The formation of ion occurs when an atom that is said to be neutral gains or losses electrons.

At the time it gains electrons, it is regarded that a negative ion (anion) is formed.

When it loses electron, it is regarded that a positive ion (cation) is formed.

Atomic number = No of protons and electrons occurring in a neutral atom.

Given that:

Protons = 14

electron = 18

Net Charge = no of proton - no of electron

= 14 - 18

= -4

Mass number = 14 + 15 = 29

So, the chemical symbol = $Si^{-4}$

For ion with

27 proton, 32 neutrons and 25 electrons

Net charge = 27 - 25

= +2

Mass number = 27 + 32 = 59

Thus, the chemical symbol = $Co^{+2}$

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Explain why vanadium (radius=134 pm) and copper (radius=128 pm) have nearly identical atomic radii, even though the atomic numbe

Viktor [21]

There are few main factors affecting the atomic radii, the outermost electrons and the protons in the nucleus and also the shielding of the internal electrons. I would speculate that the difference in radii is given by the electron clouds since the electrons difference in these two elements is in the d orbital and both has at least 1 electron in the 4s (this 4s electron is the outermost electron in all the transition metals of this period). The atomic radio will be mostly dependent of these 4s electrons than in the d electrons. Besides that, you can see that increasing the atomic number will increase the number of protons in the nucleus decreasing the ratio of the atoms along a period. The Cu is an exception and will accommodate one of the 4s electrons in the p orbital.

Regarding the density you can find the density of Cu = 8.96g/cm3 and vanadium = 6.0g/cm3. This also correlates with the idea that if these two atoms have similar volume and one has more mass (more protons; density is the relationship between m/V), then a bigger mass for a similar volume will result in a bigger density.

7 0

3 years ago

At a festival, spherical balloons with a radius of 170.cm are to be inflated with hot air and released. The air at the festival

MissTica

Answer:

The correct answer is 1.5 balloons.

Explanation:

Based on the given question, the radius of the spherical balloons is 170 cm. Therefore, the volume of each balloon will be,

= 4/3 × π × (170)³ cm³

= 20.5176 × 10⁶ cm³

= 20.5176 m³

The density of air at 100 degree C s 0.946 Kg m⁻³

The mass of air in each balloon can be calculated by using the formula,

Mass = density × volume

Mass = 0.946 Kg m⁻³ × 20.5176 m³

Mass = 19.410 Kg

The heat energy, that is, required to bring the air from 25 degree C to 100 degree C will be,

= 19.410 × 10³ g × (100 -25) degree C × 1.009 J/g degree C

= 14.68 × 10⁵ J

The concentration of butane given is 1.00 Kg or 1000 g

The molecular weight of butane is 58.12 g per mole

The moles or n can be calculated by using the formula,

n = mass / mol.wt

n = 1000 g/58.12 g/mol = 17.20 mol

The formation of enthalpy of butane at 25 degree C is 125.7 × 10³ J/mol. The evolution of heat energy that take place at the time of burning 17.20 moles of butane is,

= 125.7 × 10³ J/mol × 17.20 mol

= 2.16 × 10⁶ J

The number of balloons that can be inflated with hot air is,

= 2.16 × 10⁶ J / 14.68 × 10⁵ J per each balloon

= 1.5 balloons

Hence, maximum of 1.5 balloons can be inflated.

7 0

3 years ago

Consider the reaction: 2NO(g) + 2H2(g) → N2(g) + 2H2O(g) A suggested mechanism for this reaction follows: (1) NO(g) + NO(g) → N2

Dominik [7]

Hello. This question is incomplete. The full question is:

"Consider the following reaction. 2NO(g) + 2H2(g) → N2(g) + 2H2O(g)

A proposed reaction mechanism is: NO(g) + NO(g) N2O2(g) fast N2O2(g) + H2(g) → N2O(g) + H2O(g) slow N2O(g) + H2(g) → N2(g) + H2O(g) fast

What is the rate expression? A. rate = k[H2] [NO]2 B. rate = k[N2O2] [H2] C. rate = k[NO]2 [H2]2 D. rate = k[NO]2 [N2O2]2 [H2]"

Answer:

A. rate = k[H2] [NO]2

Explanation:

A reaction mechanism is a term used to describe a set of phases that make up a chemical reaction. In these phases a detailed sequence of each step is shown, composed of several complementary reactions, which occur during a chemical reaction.

These mechanisms are directly related to chemical kinetics and allow changes in reaction rates to be observed in advance.

Reaction rate, on the other hand, refers to the speed at which chemical reactions occur.

Based on this, we can observe through the reaction mechanism shown in the question above, that the action "k [H2] [NO] 2" would have no changes in the reaction rate.

4 0

3 years ago

In an electrolytic cell, the magnitude of the standard cell potential is the:______

melamori03 [73]

Answer:

a. minimum voltage that must be supplied for a redox reaction to occur

c. always equal to Eanode - Ecathode

Explanation:

In an electrolytic cell; The electromotive force(the maximum standard potential difference) of the cell formed by the system is defined as the standard electrode potential of the right handed electrode minus the standard electrode potential of the left hand electrode. (i.e $\mathbf{E^{\theta}_{cell}=E_{anode} - E_{cathode}}$ )

As we all known that the process by which chemical energy is being converted to electrical energy is called the Electrochemical cell. It consists of two half cells , an oxidation half cell reaction and a reduction half-cell reaction.The overall redox reaction results in a flow of electrons in an electric current which is produced by a minimum voltage.

Therefore, option a and c are both correct.

6 0

3 years ago

Complete and balance the molecular equation for the reaction of aqueous sodium carbonate, Na 2 CO 3 Na2CO3 , and aqueous nickel(

antoniya [11.8K]

Answer: The net ionic equation is written below.

Explanation:

Net ionic equation of any reaction does not include any spectator ions.

Spectator ions are defined as the ions which does not get involved in a chemical equation. They are found on both the sides of the chemical reaction when it is present in ionic form.

The chemical equation for the reaction of sodium carbonate and nickel (II) chloride is given as:

$Na_2CO_3(aq.)+NiCl_2(aq.)\rightarrow 2NaCl(aq.)+NiCO_3(s)$

Ionic form of the above equation follows:

$2Na^{+}(aq.)+CO_3^{2-}(aq.)+Ni^{2+}(aq.)+2Cl^{-}(aq.)\rightarrow NiCO_3(s)+2Na^+(aq.)+2Cl^-(aq.)$

As, sodium and chloride ions are present on both the sides of the reaction. Thus, it will not be present in the net ionic equation and are spectator ions.

The net ionic equation for the above reaction follows:

$Ni^{2+}(aq.)+CO_3^{2-}(aq.)\rightarrow NiCO_3(s)$

Hence, the net ionic equation is written above.

3 0

3 years ago