How many moles of gas does it take to occupy 25.6 liters at a pressure of 6.2 atmospheres and a temperature of 309.3 K?

Determine the a) energy (in eV) and b) wavelength (in cm) corresponding to blue light of frequency 670 THz

Lesechka [4]

Answer :

(a) The energy of blue light (in eV) is 2.77 eV

(b) The wavelength of blue light is $4\times 10^{-5}cm$

Explanation:

The relation between the energy and frequency is:

$Energy=h\times Frequency$

where,

h = Plank's constant = $6.626\times 10^{-34}J.s$

Given :

Frequency = $670THz=670\times 10^{12}s^{-1}$

Conversion used :

$1THz=10^{12}Hz\\1Hz=1s^{-1}\\1THz=10^{12}s^{-1}$

So,

$Energy=(6.626\times 10^{-34}J.s)\times (670\times 10^{12}s^{-1})$

$Energy=4.44\times 10^{-19}J$

Also,

$1J=6.24\times 10^{18}eV$

So,

$Energy=(4.44\times 10^{-19})\times (6.24\times 10^{18}eV)$

$Energy=2.77eV$

The energy of blue light (in eV) is 2.77 eV

The relation between frequency and wavelength is shown below as:

$Frequency=\frac{c}{Wavelength}$

Where,

c = the speed of light = $3\times 10^8m/s$

Frequency = $670\times 10^{12}s^{-1}$

So, Wavelength is:

$670\times 10^{12}s^{-1}=\frac{3\times 10^8m/s}{Wavelength}$

$Wavelength=\frac{3\times 10^8m/s}{670\times 10^{12}s^{-1}}=4\times 10^{-7}m=4\times 10^{-5}cm$

Conversion used : $1m=100cm$

The wavelength of blue light is $4\times 10^{-5}cm$

7 0

4 years ago

When neutralizing your acid extracts, you determined how much base solution was needed to fully neutralize your acid and reach a

alukav5142 [94]

Answer:

The amount of base needed is the amount that would give one mole of the hydroxide ion needed to neutralise one mole of the hydroxonium ion from the acid.

Explanation:

The chemical reaction between an acid and a base to form salt and water only is called a Neutralization reaction. Chemically

H⁺ + OH⁻ = H₂0

Hence, one mole of hydroxonium ion (H⁺) will combine with one mole of hydroxide ion (OH⁻) to give salt and water only.

In a completely neutralized reaction, the resulting salt is formed when there is complete dissociation of the acid and base to give salt and water with a pH of 7.

In the given question, the stated pH of between 8-9 tells us that the salt produced in this particular neutralization reaction is basic or alkaline. This usually occurs when a strong base reacts with a weak acid, producing a higher concentration of the hydroxide ion at equilibrium.

Hence the amount of base needed is the amount that would give one mole of the hydroxide ion needed to neutralise one mole of the hydroxonium ion from the acid.

If the concentration or molarity of the acid is known, then the exact amount of base required to neutralize it can be calculated. This is usually done via titrating the acid against drop wise solution of the base. Neutralization usually occurs when there is a change in colour of the resulting solution. The pH of the resulting solution can be determined using a litmus paper.

A blue litmus paper is indicative of a basic solution while a red litmus paper is indicative of an acidic solution.

6 0

3 years ago

A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. What is the weight/

lara31 [8.8K]

Answer:

A solution is made by dissolving 4.87 g of potassium nitrate in water to a final volume of 86.4 mL solution. The weight/weight % or percent by mass of the solute is :

2.67%

Explanation:

Note : Look at the density of potassium nitrate in water if given in the question.

You are calculating weight /Volume not weight/weight % or percent by mass of the solute

Here the weight/weight % or percent by mass of the solute is asked : So first convert the VOLUME OF SOLUTION into MASS

Density of potassium nitrate in water KNO3 = 2.11 g/mL

$density=\frac{mass}{volume}$

Density = 2.11 g/mL

Volume of solution = 86.4 mL

$2.11=\frac{mass}{86.4}$

$mass = 2.11\times 86.4$

$mass=182.3grams$

Mass of Solute = 4.87 g

Mass of Solution = 183.2 g

w/w% of the solute =

$= \frac{mass\ of\ solute}{mass\ of\ solution}\times 100$

$=\frac{4.87}{183.2}\times 100$

w/w%=2.67%

8 0

3 years ago

Pressure is defined as _______.1

Yakvenalex [24]

Answer:the perpendicular force per unit area

pressure, in the physical sciences, the perpendicular force per unit area, or the stress at a point within a confined fluid.

Explanation:

mark me brainliest!!

7 0

2 years ago

How many grams of H2SO4 are needed to prepare 500. mL of a .250M solution?

zavuch27 [327]

Answer:

We need 12.26 grams H2SO4

Explanation:

Step 1: Data given

Volume of a H2SO4 solution = 500 mL = 0.500 L

Concentration of the H2SO4 solution = 0.250 M

Molar mass of H2SO4 = 98.08 g/mol

Step 2: Calculate moles H2SO4

Moles H2SO4 = concentration * volume

Moles H2SO4 = 0.250 M * 0.500 L

Moles H2SO4 = 0.125 moles

Step 3: Calculate mass of H2SO4

Mass of H2SO4 = moles * molar mass

Mass of H2SO4 = 0.125 moles * 98.08 g/mol

Mass of H2SO4 = 12.26 grams

We need 12.26 grams H2SO4

7 0

3 years ago