18. Investigue por qué en el bloque "d" se aplica la fórmula n-1 y en el bloque "f" n-2.​

Answers

Answer 1

Answer:

La razón de esto es porque los elementos en el bloque d tienen sus electrones d en la capa (n-1) (penúltima capa) y puede usar electrones de la capa (n-1) (penúltima capa) para formar enlaces químicos.

Los elementos en el bloque f tienen sus electrones f en sus capas (n-2) y pueden llegar a usar electrones de la capa (n-2) (capa antes de la penúltima capa) para enlaces químicos.

Explanation:

Para explicar esto, comencemos con los elementos de bloque syp; Los elementos de bloque syp usan electrones que tienen el mismo número cuántico principal para enlaces químicos. Por ejemplo, el aluminio utiliza los electrones 3s más externos y el carbono los electrones 2s y 2p cuando forman enlaces químicos. A pesar de que el carbono (bloque p) utiliza electrones de dos conjuntos de orbitales (2s, 2p) para la unión covalente, su número cuántico principal es el mismo (2) ya que todavía provienen de la misma capa.

Pero, los metales de transición (elementos de bloque d) usan electrones del orbital "s" de la capa más externa y los orbitales "d" de la penúltima capa forman enlaces químicos. Por ejemplo, los elementos de la primera serie de transición como el manganeso, el cobre y el hierro pueden usar los electrones 4s más externos y los electrones 3d de la penúltima capa, con diferentes números cuánticos principales (4 y 3). Eso significa que los metales de transición pueden usar tanto el orbital ‘ns’ más externo como los orbitales d (n-1) de la penúltima caparazón.

Luego, para los metales de transición internos (elementos de bloque f), tienen sus electrones f en sus capas (n-2) y pueden llegar a usar electrones de la capa (n-2) (capa antes de la penúltima capa) para enlaces químicos.

¡¡¡Espero que esto ayude!!!


Related Questions

How many atoms are in 16.1 G Sr

Answers

Answer: There are [tex]1.11\times 10^{23}[/tex] atoms of Sr

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number [tex]6.023\times 10^{23}[/tex] of particles.

To calculate the moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text {Molar mass}}=\frac{16.1g}{87.6g/mol}=0.184moles[/tex]

1 mole of Sr contains =  [tex]6.023\times 10^{23}[/tex] atoms of Sr

Thus 0.184 moles of Sr contains =  [tex]\frac{6.023\times 10^{23}}{1}\times 0.184=1.11\times 10^{23}[/tex] atoms of Sr

Thus there are [tex]1.11\times 10^{23}[/tex] atoms of Sr

Which of the following aqueous solutions are good buffer systems?
0.31 M ammonium bromide + 0.39 M ammonia
0.31 M nitrous acid + 0.25 M potassium nitrite
0.21 M perchloric acid + 0.21 M potassium perchlorate
0.16 M potassium cyanide + 0.21 M hydrocyanic acid
0.14 M hypochlorous acid + 0.21 M sodium hypochlorite
0.13 M nitrous acid + 0.12 M potassium nitrite
0.15 M potassium hydroxide + 0.22 M potassium bromide
0.23 M hydrobromic acid + 0.20 M potassium bromide
0.34 M calcium iodide + 0.29 M potassium iodide
0.33 M ammonia + 0.30 M sodium hydroxide
0.20 M nitrous acid + 0.18 M potassium nitrite
0.30 M ammonia + 0.34 M ammonium bromide
0.29 M hydrobromic acid + 0.22 M sodium bromide
0.17 M calcium hydroxide + 0.28 M calcium bromide
0.34 M potassium iodide + 0.27 M potassium bromide

Answers

Answer:

Answers are in the explanation.

Explanation:

A buffer is defined as the aqueous mixture of a weak acid and its conjugate base or vice versa. Having this in mind:

0.31 M ammonium bromide + 0.39 M ammonia . Is a good buffer system because ammonia is a weak base and its conjugate base, ammonium ion is in the solution.

0.31 M nitrous acid + 0.25 M potassium nitrite . Is a good buffer system because nitrous acid is the weak acid and nitrite ion its conjugate base.

0.21 M perchloric acid + 0.21 M potassium perchlorate . Perchloric acid is a strong acid. Thus, Is not a good buffer system.

0.16 M potassium cyanide + 0.21 M hydrocyanic acid . Hydrocyanic acid is a weak acid and cyanide ion is its conjugate base. Is a good buffer system.

0.14 M hypochlorous acid + 0.21 M sodium hypochlorite . Hypochlorous acid is a weak acid and hypochlorite ion its conjugate base. Is a good buffer system.

0.13 M nitrous acid + 0.12 M potassium nitrite . Is a good buffer system as I explained yet.

0.15 M potassium hydroxide + 0.22 M potassium bromide . Potassium hydroxide is a strong base. Is not a good buffer system.

0.23 M hydrobromic acid + 0.20 M potassium bromide . HBr is a strong acid. Is not a good buffer system.

0.34 M calcium iodide + 0.29 M potassium iodide . CaI and KI are both salts, Is not a good buffer system.

0.33 M ammonia + 0.30 M sodium hydroxide . Ammonia is a weak base but its conjugate base ammonium ion is not in solution. Is not a good buffer system.

0.20 M nitrous acid + 0.18 M potassium nitrite . Is a good buffer system.

0.30 M ammonia + 0.34 M ammonium bromide . Ammonia and ammonium in solution, Good buffer system.

0.29 M hydrobromic acid + 0.22 M sodium bromide . HBr is a strong acid, is not a good buffer system.

0.17 M calcium hydroxide + 0.28 M calcium bromide . CaOH is a strong base, is not a good buffer system.

0.34 M potassium iodide + 0.27 M potassium bromide. KI and KBr are both salts, is not a good buffer system.

calculate the energy in joules and calories required to heat 50.0g silver from 106c to 255c. ​

Answers

Answer:

Explanation:

use this fromula

q = m c ∆t

m  is mass of silver =50 g

∆t is difference in temperature= 255-106=149

C=  specific heat fo silver ( should be mentioned in your question )

how to use VBT to draw the orbital overlapping diagram ​

Answers

Answer:

from the valence elecrtons configuration is the centre atom.atomised the number of elecrtons pair determine the hybridization .

Explanation:

you can read this note to know the ans

g Determine the empirical formula for a compound that contains C, H and O. It contains 40.92% C, 4.58% H, and 54.50% O by mass. Must show your work on scratch paper to receive credit.

Answers

Answer:

The empirical formula for the compound is C3H4O3

Explanation:

The following data were obtained from the question:

Carbon (C) = 40.92%

Hydrogen (H) = 4.58%

Oxygen (O) = 54.50%

The empirical formula for the compound can be obtained as follow:

C = 40.92%

H = 4.58%

O = 54.50%

Divide by their molar mass

C = 40.92/12 = 3.41

H = 4.58/1 = 4.58

O = 54.50/16 = 3.41

Divide by the smallest i.e 3.41

C = 3.41/3.41 = 1

H = 4.58/3.41 = 1.3

O = 3.41/3.41 = 1

Multiply through by 3 to express in whole number

C = 1 x 3 = 3

H = 1.3 x 3 = 4

O = 1 x 3 = 3

The empirical formula for the compound is C3H4O3

Which describes an effect that ocean currents have on short-term climate change? Ocean currents increase the strength of prevailing winds, which can cool the air and land. Ocean currents can carry cold water, which can cool the air and land. Ocean currents increase hurricane activity, which can raise the temperature of the air and land. Ocean currents can carry warm water, which causes hurricane activity and raises the temperature of the air and land.

Answers

Answer:  B

Ocean currents can carry cold water, which can cool the air and land.

Explanation:

eet ees wat eet ees

plz mark brainliest

Answer:

B is right

Explanation:

which proess is part of the carbon cycle

Answers

Answer:

The key processes in the carbon cycle are: carbon dioxide from the atmosphere is converted into plant material in the biosphere by photosynthesis.

Explanation:

organisms in the biosphere obtain energy by respiration and so release carbon dioxide that was originally trapped by photosynthesis. ... The carbon becomes part of the .

Which diagram represents the bonding pattern of metals?

Answers

Answer:

there's no image can't help without it sorry

In supersonic flights, molecules break apart and react chemically. which safety features protect the plane?

Answers

Answer:

Explanation:

The heat Shield are materials (usually made of  metals) protect us from heat by  absoring lots of heat and gradually releasing heat by surrounding  air cirucaltion

Answer:

Heat shield

Explanation: Most heat shields consist of one or more layers of stamped metal that are shaped into a shield that is designed to wrap around the exhaust manifold. The shield acts as a barrier and heat sink, preventing the heat from the manifold from reaching any of the components under the hood and potentially causing damage.

Combustion of hydrocarbons such as nonane () produces carbon dioxide, a "greenhouse gas." Greenhouse gases in the Earth's atmosphere can trap the Sun's heat, raising the average temperature of the Earth. For this reason there has been a great deal of international discussion about whether to regulate the production of carbon dioxide. 1. Write a balanced chemical equation, including physical state symbols, for the combustion of liquid nonane into gaseous carbon dioxide and gaseous water. 2. Suppose of nonane are burned in air at a pressure of exactly and a temperature of . Calculate the volume of carbon dioxide gas that is produced. Round your answer to significant digits.

Answers

Answer:

Part 1: C₉H₂₀ (l) + 14O₂ (g) ----> 9CO₂ (g) + 10H₂0 (g)

Part 2: Volume of CO₂ produced = 1223.21 L

Note: the complete second part of the question is given below:

2. Suppose 0.470 kg of nonane are burned in air at a pressure of exactly 1 atm and a temperature of 17.0 °C. Calculate the volume of carbon dioxide gas that is produced. Round your answer to 3 significant digits.

Explanation:

Part 1: Balanced chemical equation

C₉H₂₀ (l) + 14O₂ (g) ----> 9CO₂ (g) + 10H₂0 (g)

Part 2: volume of carbon dioxide produced

From the equation of the reaction;

At s.t.p., I mole of  C₉H₂₀ reacts with 14 moles of O₂ to produce 9 moles of CO₂

molar mass of  C₉H₂₀  = 128g/mol: molar mass of CO₂ = 44 g/mol, molar volume of gas at s.t.p. = 22.4 L

Therefore, 128 g of C₉H₂₀ produces 14 * 22.4 L of CO₂ i.e. 313.6 L of CO₂.

O.470 Kg  of nonane = 470 g of nonane

470 g of C₉H₂₀ will produce 470 * (313.6/128) L of CO₂ = 1151.50 L of CO₂

Volume of CO₂ gas produced at 1 atm and 17 °C;

Using P₁V₁/T₁ = P₂V₂/T₂

V₂ = P₁V₁T₂/P₂T₁

where P₁ = 1 atm, V₁ = 1151.50 L, T₁ = 273 K, P₂ = 1 atm, T₂ = 17 + 273 = 290 K

Substituting the values; V₂ = (1 * 1151.5 * 290)/(1 * 273)

Therefore volume of CO₂ produced, V₂ = 1223.21 L of CO₂

Which represents the size of a population?
the birth rate
number of species in an area
the death rate
number of indivduals in a species
Pls hurry

Answers

Answer:

The Answer is D

Explanation:

Populations are shown by seeing how many speecies are in the area.

The number of individuals in a species represents the size of a population. hence, the last option is correct.

What is the population size?

It is the actual no of individuals in the population.

The density of the population refers to the measurement of population size for per unit area.

So based on this, we can say that The number of individuals in a species represents the size of a population. hence, the last option is correct.

Learn more about population here: https://brainly.com/question/16381226

a) What is the common-ion effect?b) Given an example of a salt that can decrease the ionization of HNO2 in solution. List all of the substances (species) that would be present in the solution. (Consider the HNO2, the salt, and the water.)

Answers

Answer:

Common ion effect refers to the decrease in the solubility of a substance in a solution with which it shares a common ion.

NaNO2

Explanation:

In order to understand exactly what common ion effect is, let us consider a simple unambiguous example. Assuming I have a solution of an ionic substance that contains a cation A and an anion B, this ionic substance has chemical formula AB. Secondly, I have another ionic distance with cation C and anion B, its chemical formula is CB. Both CB and AB are soluble in water to a certain degree as shown by their respective KSp.

If I dissolve AB in water and form a solution, subsequently, I add solid CB to this solution, the solubility of CB in this solution is found to be lees than the solubility of CB in pure water because of the ion B^- which is common to both substances in solution. We refer to the phenomenon described above as common ion effect.

Common ion effect refers to the decrease in the solubility of a substance in a solution with which it shares a common ion.

If I try to dissolve NaNO2 in a solution of HNO2, the solubility of NaNO2 in the HNO2 solution will be less than its solubility in pure water due to common ion effect. Also, the extent of ionization of HNO2 in a system that already contains NaNO2 will be decreased compared to its extent ionization in pure water. This system described here will contain HNO2, water and NaNO2

Using the Henderson-Hasselbalch equation, calculate the percentage of an ammonia solution that would be in the ionic form at pH 9.40, assuming a pKa for the ammonium ion of 9.25.

Answers

Answer:

41.45% is the precentage of the ionic form

Explanation:

H-H equation is used to find pH of a buffer. The formula is:

pH = pKa + log₁₀ [X⁻] / [HX]

Where X⁻ is the conjugate base of the weak acid, HX.

In the ammonia buffer:

NH₄⁺ ⇄ NH₃ + H⁺

NH₄⁺ is the weak acid (Ionic form) and NH₃ is the conjugate base. Replacing:

9.40 = 9.25 + log₁₀ [NH₃] / [NH₄⁺]

1.4125 = [NH₃] / [NH₄⁺] (1)

In a percentage, [NH₃] + [NH₄⁺] = 100 (2)

Replacing (2) in (1):

1.4125 = 100 - [NH₄⁺] / [NH₄⁺]

1.4125[NH₄⁺] = 100 - [NH₄⁺]

2.4125[NH₄⁺] = 100

[NH₄⁺] = 41.45% is the precentage of the ionic form

The percentage of an ammonia solution is 41.5%

The Henderson Hasselbalch equation is an approximation that demonstrates the relation among a solution's pH or pOH, as well as the concentration ratio for the dissociated chemical species.

The dissociation of ammonium ion in the buffer is as follow:

[tex]\mathbf{NH_4^+ \to NH_3 + H^+}[/tex]

The Henderson Hasselbalch equation for the dissociation of ammonium can be expressed by using the formula:

[tex]\mathbf{pH = pKa + log \dfrac{[NH_3 ] }{[ NH_4^+] }}[/tex]

Given that:

pH = 9.40pKa = 9.25

[tex]\mathbf{9.40= 9.25 + log \dfrac{[NH_3 ] }{[ NH_4^+] }}[/tex]

[tex]\mathbf{9.40- 9.25 = log \dfrac{[NH_3 ] }{[ NH_4^+] }}[/tex]

[tex]\mathbf{0.15 = log \dfrac{[NH_3 ] }{[ NH_4^+] }}[/tex]

[tex]\mathbf{10^{0.15} = \dfrac{[NH_3 ] }{[ NH_4^+] }}[/tex]

[tex]\mathbf{1.41 = \dfrac{[NH_3 ] }{[ NH_4^+] }}[/tex]

[tex]\mathbf{\dfrac{141}{100} = \dfrac{[NH_3 ] }{[ NH_4^+] }}[/tex]

The percentage of NH₄⁺ [tex]\mathbf{= \dfrac{141}{100+141}\times 100\%}[/tex]

= 58.5%

The percentage of NH₃ [tex]\mathbf{= \dfrac{100}{100+141} \times 100\%}[/tex]

= 41.5%

Learn more about the Henderson-Hasselbalch equation here:

https://brainly.com/question/13651361

Part A Find ΔErxn for the combustion of biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/∘C. Express the energy in kilojoules per mole to three significant figures.

Answers

Question:

When 0.500 g of biphenyl (C₁₂H₁₀) undergoes combustion in a bomb calorimeter, the temperature rises from 26.8 °C to 29.5 °C. Part A Find ΔErxn for the combustion of biphenyl. The heat capacity of the bomb calorimeter, determined in a separate experiment, is 5.86 kJ/∘C. Express the energy in kilojoules per mole to three significant figures.

Answer;

-4870kJ/mol(3 significant figure)

Calculate the temperature and state the appropriate phase(s) (solid, liquid, vapor) for each substance: This temperature is: Fahrenheit A. SubstanceMelting Point (K)Boiling Point (K)Phase(s) Oxygen, O254.7590.19 Methane, CH493.15109.10 Water, H2O273.15373.15

Answers

Answer:

Explanation:

At 54.75K melting point, Oxygen is in gas (vapour) phase

At 373.15K boiling point, water is in liquid phase.

At 109.10K boiling point methane is in gas (vapour) phase.

An electron in a 3s3s orbital penetrates into the region occupied by core electrons more than electrons in a 3p3p orbital. An electron in a orbital penetrates into the region occupied by core electrons more than electrons in a orbital. true false

Answers

Answer:

True

Explanation:

The penetrating ability of electrons in the orbitals is in the order s > p > d > f

An electron in a 3s orbital is closer to the nucleus than the one in a 3p orbital and as a result, there will be lesser shielding effect on it. This low shielding effect experienced by the 3s electron gives it a high penetration ability and hence will be able to easily penetrate regions occupied by core electrons. Conversely, the 3p orbital is farther away from the nucleus, electrons revolving around it are highly shielded which limits their ability to penetrate regions of core electrons.

Note that the maximum electrons that the s orbital can accommodate is 2 while p orbital can accommodate a maximum of 8.

A scientist measures the standard enthalpy change for the following reaction to be -115.5 kJ: CO(g) + Cl2(g)___COCl2(g) Based on this value and the standard enthalpies of formation for the other substances, the standard enthalpy of formation of COCl2(g) is ________ kJ/mol.

Answers

Answer:

-226.0kJ = ΔH°f COCl₂(g)

Explanation:

Using Hess' law, it is possible to obtain the enthalpy of formation of a substance from the enthalpy change of a reaction and the other enthalpies of formation involved in the reaction.

For the reaction:

CO(g) + Cl₂(g) → COCl₂(g)

Hess's law is:

ΔHr = -115.5kJ = ΔH°f COCl₂(g) - (ΔH°f CO(g) + ΔH°f Cl₂(g))

ΔH°f CO(g) is -110.5kJ/mol

ΔH°f Cl₂(g) is 0 kJ/mol

Replacing in Hess's law:

-115.5kJ = ΔH°f COCl₂(g) - (-110.5kJ/mol + 0kJ/mol)

-115.5kJ = ΔH°f COCl₂(g) + 110.5kJ

-226.0kJ = ΔH°f COCl₂(g)

When 2,2-dimethylbutane is subjected to free-radical chlorination, ________ distinct monochlorinated products are possible and ________ of these contain asymmetric carbon atoms.

Answers

Answer:

See the explanation

Explanation:

In this case, we have to remember that in the monochlorination products we only have to add one "Cl" with this in mind, we can have several options.

a) 1-chloro-2,2-dimethylbutane

b) (R)-3-chloro-2,2-dimethylbutane

c) (S)-3-chloro-2,2-dimethylbutane

d) 1-chloro-3,3-dimethylbutane

Additionally, from these 4 molecules, we will have 2 enantiomers. (R)-3-chloro-2,2-dimethylbutane and (S)-3-chloro-2,2-dimethylbutane.

See figure 1

I hope it helps!

There four distinct monochlorinated products and two of them contain an asymmetric carbon atom.

Free radicals refers to chemical species that posses an odd number of electrons. An asymmetric carbon atom is a carbon atom that is bonded to four different groups.

When 2,2-dimethylbutane is subjected to free-radical chlorination, four distinct monochlorinated products are possible and two of these contain asymmetric carbon atoms.

The  four distinct monochlorinated products are;

1-chloro-2,2-dimethylbutane (R)-3-chloro-2,2-dimethylbutane  (S)-3-chloro-2,2-dimethylbutane  1-chloro-3,3-dimethylbutane

Learn more: https://brainly.com/question/9743981

You are titrating 25.025.0 mL of 0.0100 M Sn2 Sn2 in 1 M HCl HCl with 0.0500 M Tl3 Tl3 resulting in the formation of Sn4 Sn4 and Tl Tl . A PtPt indicator electrode and a saturated Ag|AgCl Ag|AgCl reference electrode are used to monitor the titration. What is the balanced titration reaction

Answers

Answer:

Sn²⁺ + Tl³⁺ → Sn⁴⁺ + Tl⁺

Explanation:

The Sn²⁺ is oxidized to Sn⁴⁺. Whereas Tl³⁺ is reduced to Tl⁺. The half-reactions are:

Sn²⁺ → 2e⁻ + Sn⁴⁺ (Oxidation, loosing electrons)

Tl³⁺ + 2e⁻ →Tl⁺ (Reduction, gaining electrons)

The sum of the reactions gives:

Sn²⁺ + Tl³⁺ + 2e⁻ → 2e⁻ + Sn⁴⁺ + Tl⁺

Subtracting the electrons in both sides of the reaction:

Sn²⁺ + Tl³⁺ → Sn⁴⁺ + Tl⁺

Give the expressions for the disappearance of the reactants first, in the order written in the chemical equation. Then write the expressions for the appearance of the products in the order written in the chemical equation.

Write the expressions in order of appearance in the equation in the form.

± 1/X . Δ[A]/ Δt

where ± is either a plus OR a minus sign, not both,
X is an integer, and
A is a chemical species.

4NH3(g)+ 5O2(g) → 4NO2+ 6H2O(g)

Answers

Answer: Rate of disappearance of [tex]NH_3[/tex] = [tex]\frac{-\Delta [NH_3]}{4dt}][/tex]

Rate of disappearance of [tex]O_2[/tex] = [tex]\frac{-\Delta [O_2]}{5dt}[/tex]

Rate of appearance of [tex]NO_2[/tex] = [tex]\frac{+\Delta [NO_2]}{4dt}[/tex]

Rate of appearance of [tex]H_2O[/tex] = [tex]\frac{+\Delta [H_2O]}{6dt}[/tex]

Explanation:

Rate law says that rate of a reaction is directly proportional to the concentration of the reactants each raised to a stoichiometric coefficient determined experimentally called as order.

The rate in terms of reactants is given as negative as the concentration of reactants is decreasing with time whereas the rate in terms of products is given as positive as the concentration of products is increasing with time.

For the given chemical equation :

[tex]4NH_3(g)+5O_2(g)\rightarrow 4NO_2(g)+6H_2O(g)[/tex]

Rate of disappearance of [tex]NH_3[/tex] = [tex]\frac{-\Delta [NH_3]}{4dt}][/tex]

Rate of disappearance of [tex]O_2[/tex] = [tex]\frac{-\Delta [O_2]}{5dt}[/tex]

Rate of appearance of [tex]NO_2[/tex] = [tex]\frac{+\Delta [NO_2]}{4dt}[/tex]

Rate of appearance of [tex]H_2O[/tex] = [tex]\frac{+\Delta [H_2O]}{6dt}[/tex]

Water is placed in a graduated cylinder and the volume is recorded as 43.5 mL. A homogeneous sample of metal pellets with a mass of 10.88 g is added and the volume of the water now reads 49.4 mL. What is the density of the metal in g/mL? Multiple Choice 10.9 1.8 0.250 1.6 0.541

Answers

Answer:

1.8g

Explanation:

Initial volume = 43.5ml

Final volume = 49.4ml

Mass = 10.88g

Density = ?

Volume = Final volume - initial volume

= 49.4 - 43.5

= 5.9ml

Density = Mass/volume

Density = 10.88/5.9

= 1.8g/ml

Which is regarding enzyme inhbition

Answers

Explanation:

An enzyme inhibitor is a molecule that binds to an enzyme and decreases its activity. ... Since blocking an enzyme's activity can kill a pathogen or correct a metabolic imbalance, many drugs are enzyme inhibitors. They are also used in pesticides.

In a zero order reaction, it takes 342 seconds for 75% of a hypothetical reactant to decompose. Determine the half-life t_{1/2} in units of seconds. Do not enter units with your numerical answer. Numeric Answer:

Answers

Answer:

228 s

Explanation:

In a zero order reaction, the formula for the half life is given as;

t1/2 = [A]o / 2k

To obtain the rate constant k, we have to use;

[A] = [A]o - kt

kt = [A]o - [A]

From the question;

it takes 342 seconds for 75% of a hypothetical reactant to decompose.

We have;

t = 324

[A] = 25

[A]o = 100

Upon solving for k we have;

kt = [A]o - [A]

k = ( [A]o - [A] ) / t

k = (100 - 25 ) / 342

k = 75 / 342 = 0.2193

Solving for t1/2;

t1/2 = [A]o / 2k

t1/2 = 100 / 2(0.2193)

t1/2 = 100 / 0.4386 = 228 s

In a chemical equation, which symbol should be used to indicate that a substance is in solution? (s)

Answers

Answer:

(aq) meaning aqueous solution

Explanation:

hope it helps .

If 45.5 g of a metal that has a density of 3.65 g/mL is placed in 45.0 mL of water, what is the final volume?

Answers

Answer:

The final volume of the metal and water is 54.46mL

Explanation:

Hello,

To solve this question, we'll first of all find the volume of the metal and assuming there's no loss of water by overflow in the container, we'll add the volume of the metal to the volume of the water to get the final volume.

Data;

Mass of the metal = 45.5g

Volume of the water = 45mL

Density of the metal (ρ) = 3.65g/mL

Density of the metal = mass / volume

ρ = mass / volume

Volume (v) = mass / density

Volume = 45.5 / 3.65

Volume = 12.46mL

The volume of the metal is 12.46mL.

When the metal is added to the container 45mL of water, assuming no water was lost by overflow in the container, the final volume =

Final volume = volume of metal + volume of water

Final volume = 12.46 + 45.0

Final volume = 57.46mL

The final volume of the metal and water is 57.46mL

475 grams of solid calcium oxide reacts with water vapor to form solid calcium hydroxide.Calculate the heat of reaction.
(A) - 221.1 kcal
(B) + 290.8 kcal
C) - 290.8 kcal
(D) + 324.6 kcal
(E) + 221.1 kcal​

Answers

Answer:

(A) - 221.1 kcal

Explanation:

Based in the reaction:

CaO(s) + H₂O(g) → Ca(OH)₂ ΔH = -109kJ/mol

When 1 mole of CaO reacts per mole of water vapor producing calcium hydroxide there are released -109kJ

475g of CaO (Molar mass CaO: 56.08g/mol) are:

475g CaO × (1mol / 56.08g) = 8.47 moles of CaO

As 1 mole of CaO in reaction release -109kJ, 8.47 moles release:

8.47 mol CaO × (-109 kJ / 1 mol CaO) = -923.2kJ are released

As 1 kCal = 4.184kJ:

-923.2kJ × (1kCal / 4.184kJ) =

-220.7kCal ≈ (A) - 221.1 kcal

The air in a hot-air balloon at 735 torr is heated from 22.0°C to 46.0°C. Assuming that the moles of air and the pressure remain constant, what is the density of the air at each temperature? (The average molar mass of air is 29.0 g/mol.)

Answers

Answer:

D1 = 1.16 g/L

D2 = 1.07 g/L

Explanation:

PV = mRT/M

PVM = mRT

PM/RT = m/V = D  - density

D = PM/RT

P = 735 torr

T1= 22.0°C+ 273.15 =  295.15 K

T2 = 46.0°C+ 273.15 =  319.15 K

M = 29.0 g/mol

R = 62.363 torr*L/mol*K

D1 = PM/RT1

D1 = (735 torr*29.0 g/mol) / (62.363 torr*L/mol*K *295.15 K) = 1.16 g/L

D1 = 1.16 g/L

D2 = PM/RT2

D2 = (735 torr*29.0 g/mol) / (62.363 torr*L/mol*K *319.15 K) = 1.07 g/L

D2 = 1.07 g/L

A scientist wants to make a solution of tribasic sodium phosphate, Na3PO4, for a laboratory experiment. How many grams of Na3PO4 will be needed to produce 525 mL of a solution that has a concentration of Na ions of 1.10 M

Answers

Answer:

31.652g of Na3PO4

Explanation:

We'll begin by calculating the molarity of Na3PO4 solution. This can be achieved as shown below:

Na3PO4 will dessicate in solution as follow:

Na3PO4(aq) —> 3Na+(aq) + PO4³¯(aq)

From the balanced equation above,

1 mole of Na3PO4 produce 3 moles of sodium ion, Na+.

Therefore, xM Na3PO4 will produce 1.10M sodium ion, Na+ i.e

xM Na3PO4 = (1.10 x 1)/3

xM Na3PO4 = 0.367M

Therefore, the molarity of Na3PO4 is 0.367M.

Next, we shall determine the number of mole of Na3PO4 in the solution. This is illustrated below:

Molarity of Na3PO4 = 0.367M

Volume = 525mL = 525/1000 = 0.525L

Mole of Na3PO4 =..?

Molarity = mole /Volume

0.367 = mole /0.525

Cross multiply

Mole of Na3PO4 = 0.367 x 0.525

Mole of Na3PO4 = 0.193 mole.

Finally, we shall convert 0.193 mole of Na3PO4 to grams. This is illustrated below:

Molar mass of Na3PO4 = (23x3) + 31 + (16x4) = 164g/mol

Mole of Na3PO4 = 0.193 mole

Mass of Na3PO4 =.?

Mass = mole x molar mass

Mass of Na3PO4 = 0.193 x 164

Mass of Na3PO4 = 31.652g

Therefore, 31.652g of Na3PO4 is needed to prepare the solution.

Identify each element below, and give the symbols of the other elements in its group.

a. [Ar] 4s23d104p4
b. [Xe] 6s24f145d2
c. [Ar] 4s23d5.

Answers

Answer:

Explanation:

the electron configuration is defined as the distribution of electrons of an atom or molecule in atomic or molecular orbitals. It is

used to describe the orbitals of an atom in its ground state

The valence electrons, electrons in the outermost shell, can be used to know the chemical property

a)

Chemical Name of the Element: Selenium

Chemical Symbol: Se

Group it belong in periodic table:6A

Other Element in the same group:tellurium(Te),,sulfur(S)

atomic number = 34

Selenium is a chemical element that has symbol Se It is a nonmetal which is usually classified as metalloid with properties that are intermediate between the elements above and below in the periodic table.

b)Chemical Name of the Element:Hafnium

Chemical Symbol: Hf

Group it belong in periodic table:4B

Other Element in the same group: Titanium( Ti )Rutherfordium

atomic number: 72

Hafnium is a solid at room temperature.

c)Chemical Name of the Element: Manganese

Chemical Symbol:Mg

Group it belong in periodic table:Mn

Other Element in the same group:Bohrium(Bh) ,Technetium(Tc)

Will GIVE BRAINLIEST ---A student makes a standard solution of potassium hydroxide by adding 14.555 g to 500.0 mL of water.
Answer the following questions, being sure to include units and remember sig figs. Show your work.
a. What is the concentration of this standard solution?

Answers

Answer:

a) 0.5198 mol/L

b) 0.00811 mol KOH

Explanation:

a) M(KOH) = 39+16+1= 56 g/mol

14.555g* 1 mol/56 g = 14.555/56 mol  KOH in 500.0 mL solution

14.555/56 mol  KOH ---- 0.5000 L solution

x mol KOH               ----- 1 L solution

x = (14.555/56)mol * 1L/0.5000 L = 0.5198 mol/L

b) If the student pours out a 15.6 mL sample of this solution, how many moles of sodium hydroxide? (if we talk about KOH)

does the student have in the sample

15.6 mL = 0.0156 L

0.5198 mol/L * 0.0156 L = 0.00811 mol KOH

Molarity is an important method which is used to determine the concentration of a solution. The concentration of the standard solution containing 14.555 g to 500.0 mL of water is 29.11 mol L⁻¹.

What is molarity?

The molarity of a solution is an important method which is used to calculate the concentration of a binary solution which contains the solute and solvent. It is defined as the number of moles of the solute present per litre of the solution.

The molarity is generally represented by the letter 'M' and its unit is mol L⁻¹. The equation used to calculate the molarity is given as:

Molarity = Number of moles of the solute / Volume of the solution in litres

500.0 mL = 0.5 L

M = 14.555 / 0.5 = 29.11 mol L⁻¹

Thus the concentration of a solution is  29.11 mol L⁻¹.

To know more about concentration, visit;

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