### After the reaction, how much octane is left?

The chemical equation for the reaction is given below: [ C_8H_{18} + 25/2 O_2 rightarrow 8CO_2 + 9H_2O ] In this reaction, 0.430 moles of octane react with 0.890 moles of oxygen. The question aims to find the moles of octane left after the said reaction takes place. Octane is a hydrocarbon whose chemical formula […]

### Argon is compressed in a polytropic process with n=1.2 from 120 kPa and 30°C to 1200 kPa in a piston-cylinder device. Determine the final temperature of the argon.

The aim of this article is to find the final temperature of the gas after it has gone through a polytropic process of compression from lower to higher pressure. The basic concept of this article is the Polytropic process and Ideal Gas Law. The polytropic process is a thermodynamic process involving the expansion or compression […]

### The molar solubility of pbBr2 at 25 °C is 1.0×10−2mol/l. Calculate ksp.

This question aims to find the molar solubility constant $K_{sp}$ when the molar solubility of $PbBr _ 2$ is $1.0 times 10 ^ { -2 } mol/L$ at a room temperature of 25 °C. The molar solubility constant is a constant represented by $k_{sp}$ which tells the amount of salt dissolved […]

### Aqueous Iodide ion is oxidized to i2(s) by hg22+(aq).

This question aims to find the balanced equation and standard emf with the value of G and equilibrium constant K of the given reactions. The quotient of the concentration of products and the concentration of reactants is expressed by equilibrium constant K while $Delta G°$ represents the free energy during the reaction. $Delta G°$ and […]

### Which one of the following species has as many electrons as it has neutrons?

– Select the correct answer from the following options: – $(a) ^{14}C$ – $(b) ^{14}C^{2+}$ – $(c) ^{40}{rm Ca}^{2+}$ – $(d) ^1H$ – $(e) ^{19}F^-$ The aim of this article is to find the element in which the number of electrons is the same as the number of neutrons. The basic concept behind this article […]

### Calculate the ratio of effusion rates for Ar and Kr.

This question is from the chemistry domain and aims to explain the basic concepts related to the periodic table, Molar masses, the ratio of effusion rates, and Graham law to determine the effusion rate. In the periodic table, the chemicals are displayed in a tabular manner. The periodic table sometimes is also named the periodic […]

### How many hydrogen atoms are in 35.0 grams of hydrogen gas?

The aim of this question is to find the number of hydrogen atoms present in 35 grams of hydrogen gas. A molecule is made up of a number of atoms. In order to find out the number of hydrogen atoms in 35 g of hydrogen gas, the given mass of the gas is used to […]

### Select which of the following standard enthalpy of formation values is not zero at 25°C:

– Na(s) – CH_4(g) – H(g) – Hg(l) – Ne(g) – S_8(rhombic) This question aims to find out which of the above-mentioned elements/compounds has the standard enthalpy value not equal to zero at the given temperature. We will check if the given elements/compounds are in their standard state or not, after which we will define […]

### Formic acid, HCOOH, is a weak electrolyte. What solutes are present in the aqueous solution of formic acid. Write its equilibrium equation

The question aims to find the solute particles of the formic acid in an aqueous solution and the chemical equation for its ionization in water. This question is based on the concept of ionization of electrolytes. Weak electrolytes are known to not completely ionize in water. The weak electrolytes will contain ions and molecules in […]

### State how many mole ratios can be written for chemical reaction involving three substances.

This problem aims to find the mole ratio of a chemical reaction involving three chemical substances. To better understand the problem, you should know about the mole, mole weight, and mole ratios in stoichiometric reactions. A stoichiometric chemical reaction is a reaction in which the combined quantities of the reactants and products are in such […]

### The density of acetic anhydride is 1.08 g/mL. How many moles are contained in 5 mL. Please show in detail how the answer was obtained.

The aim of this question is to learn the calculations involved in molar proportions of chemical compounds. This is a three-step process. First, we find the molar mass of the given compound using its chemical formula. Second, we find the no. of moles contained in unit volume using the following formula: [ 1 mL of […]

### If we triple the average kinetic energy of the gas atoms, what is the new temperature in ∘c?

Assume that the ideal gas is at 40C.The aim of this question is to understand the relationship between temperature and kinetic energy of ideal gas molecules. The formula for the average kinetic energy of an ideal gas is: [ E = dfrac{ 3 }{ 2 } k_b T ] Where, [ E = text{ average […]

### Write a reaction that shows what happens when methanol is treated with potassium hydroxide?

The aim of this question is to find the reaction of methanol, which is an alcohol, with potassium hydroxide, which is a strong base. The basic concept behind this article is the substitution and elimination reactions of alcohols in the presence of strong basic mediums. When alcohols are mixed with a strongly basic medium, they split […]

### The matter is more likely to exist in the ________ state as the pressure is increased or temperature is decreased.

The question aims to find the state of the matter when the temperature is raised and pressure is reduced. The state of the matter highly depends on temperature and pressure. When thermal energy is added to matter, its temperature increases and the state of the matter also changes with it accordingly. When the temperature rises, […]

### An aerosol spray can with a volume of 250 mL contains 2.30 g of propane gas (C3H8) as a propellant.

-a) If the can is at $25 C$, what is the pressure in the can? -b) What volume would the propane occupy at STP? This question belongs to the chemistry domain and aims to explain the concepts of moles, molar mass, and Ideal gas equation. Furthermore, it explains how to calculate the volume and the […]

### The constant-pressure heat capacity of a sample of a perfect gas was found to vary with temperature according to the expression. Calculate q, w H and U when the temperature is raised from 25 degree to 100 degree.

– The pressure is constant. – The volume is constant. The main objective of this question is to find the work and change in enthalpy at constant pressure and constant volume. This question uses the concept of enthalpy and the first law of thermodynamics. Enthalpy is a measure of thermodynamics that corresponds to a system’s […]

### Calculate the ratio of NaF to HF required to create a buffer with pH =4.20.

This question aims to find the ratio of Sodium Fluoride (NaF) to Hydrogen Fluoride (HF) that is used to create a buffer having pH 4.20 . The pH of a solution determines whether a solution is basic or acidic. pH is measured by a pH scale which ranges from 0-14. A solution giving a pH reading […]

### Now consider an excited-state hydrogen atom, what is the energy of the electron in the n=4 level?

– Calculate the energy level of an electron in a hydrogen atom if it is considered to be in the ground state. The aim of this article is to find the energy level of electrons in a hydrogen atom when the hydrogen atom is in the ground state and excited state. The basic concept behind […]

### Enter the solubility-product expression for Al(OH)3 (s)

This question aims to develop the understanding of solubility product $k_{ sp }$ which is related to the solubility reactions and proportions. To solve this question, we may use a four-step process. Step (1) – Molar mass estimation of the subject compound employing its chemical formula. Step (2) – Mass (in grams) estimation […]

### How many atoms are in 1.75 mol CHCl3?

The goal of this question is to determine the number of atoms in $1.75,mol$ $CHCl_3$. An atom is the smallest unit in which matter can be divided without releasing electrically charged particles possessing distinctive chemical element properties. A significant proportion of the atom is an empty space. The rest of the structure is made up […]

### Calculate the ratio of NaF to HF required to create a buffer with pH=4.15.

The main objective of this question is to calculate the ratio $NaF$ to $HF$ required to create a buffer with a given $pH$. A buffer is an aqueous solution that sustains noticeable variation in $pH$ levels when a small amount of acid or alkali is added, which is made up of a weak acid and […]

### From the half-life for 14C decay, 5715 year, determine the age of the artifact.

A wooden radioactive artifact present in a Chinese Temple comprising of $^{14}C$ activity was decaying at the rate of $38.0$ counts per minute, whereas for a standard of zero age for $^{14}C$, the standard rate of decaying activity is 58.2 counts per minute. This article aims to find the age of the artifact […]

### The solubility of copper (I) chloride is 3.91 mg per 100.0 ml of solution. Calculate the value of K_sp.

This question aims to find the solubility product $k_{ sp }$ involved in the solubility reactions and proportions. This is a four-step process. First, we find the molar mass of the given compound using its chemical formula. Second, we find the mass of of given compound dissolved in 1 L solution. Third, we […]

### A 20.0 mL sample of 0.150 M ethylamine is titrated with 0.0981 M HCI. What is the pH after the addition of 5.0 mL of HCl? For ethylamine, pKb = 3.25.

The aim is to explain the concepts of pH and pOH values. How to find and calculate the pH values by seeing the amount of water in the solution. pH is a measurement of how acidic/basic the water is. The range varies from 0   – 14, where 7 denotes the neutral. The solution is said to be […]

### A piece of sodium metal reacts completely with water is given below. The hydrogen gas generated is collected over water at 25.0 degree C. The volume of the gas is 246 mL measured at 1.00 atm. Calculate the number of grams of sodium used in the reaction. (Vapor pressure of water at 25 degree C=0.0313 atm.)

The reaction is given as follows: [2Na(s) +2H_{2}O Rightarrow 2NaOH(aq) +H_{2}(g)] This article aims to determine the mass of sodium used in the given reaction. The article uses the concept of finding the number of moles and then mass from the number of moles. Ideal gas law is used to determine the number of moles of gas. Ideal […]

### A gas mixture contains 75.2% nitrogen and 24.8% krypton by mass.

If the total pressure of the mixture is 745mmHg, calculate the partial pressure acting on the krypton in that given mixture. This question aims to find the partial pressure exerted by an individual component of a gaseous mixture. The basic concept behind this article on Dalton’s Law of Partial Pressure states that the total pressure […]

### Calculate the pH of a buffer that is 0.12 M in lactic acid and 0.11 M in sodium lactate.

The question aims to find the pH of a buffer. The measure of acidity or authenticity of aqueous or other liquid solutions is defined as pH. This term is normally used in chemistry, biology, and agronomy, and translates concentrations of hydrogen ions — usually between 1 and 10−14 per gram per liter — into numbers between […]

### If the ethyl benzoate used to prepare triphenylmethanol is wet, what by product is formed?

This problem aims to familiarize us with the preparation of triphenylmethanol, which is used for numerous purposes in the laboratory for testing and preparing various dyes and intermediate products. For this problem, everything roles around the core concepts of chemical reactions, products, and their preparation. Now, Triphenylmethanol is basically an organic compound. Organic compounds are those […]

### Calculate the Molar Solubility of Ni(OH)2 when Buffered at ph=8.0

This question aims to find the molar solubility of Ni(OH)_2 when buffered at ph=8.0. The pH of a solution determines whether a solution is basic or acidic. pH is measured by a pH scale which ranges from 0-14. A solution giving a pH reading of 7 is considered neutral, whereas a solution giving a pH […]

### A 2.4 m aqueous solution of an ionic compound with the formula MX2 has a boiling point of 103.4 C. Calculate the Van’t Hoff factor (i) for MX2 at this concentration.

The aim of this problem is to familiarize us with the calculation of the concentration of an aqueous solution. The concept required to solve this problem is related to molar concentrations, Van’t Hoff factor, and abnormal molar masses. According to Van’t Hoff’s law, a rise in temperature will result in an expansion in the rate […]

### How many hydrogen atoms are in $35.0$ grams of hydrogen gas?

In order to understand the quantity of atoms in a given mass of element, we need to understand the concept of Mole. $Mole$ is defined as the mass of substance which can be an atom, molecule, electron, ion or any other particle or group of particles having $6.022times{10}^{23}$  elementary entities which is known as $Avogadro’s$ […]