Which substance has a standard enthalpy of formation of zero?.

Red light has a wavelength of 700 nm and a frequency of 4.3 x 10^14 s^-1. What is the energy of a single photon of red light?

BaLLatris [955]

Answer:

E = 2.85×10⁻¹⁹ J

Explanation:

Given data:

Wavelength of light = 700 nm

Frequency of light = 4.3×10¹⁴ s⁻¹

What is the energy of light = ?

Solution:

Formula:

E = h × f

h = plancks constant = 6.63×10⁻³⁴ Js

by putting values,

E = 6.63×10⁻³⁴ Js × 4.3×10¹⁴ s⁻¹

E = 28.5×10⁻²⁰ J

E = 2.85×10⁻¹⁹ J

6 0

3 years ago

Consider that a sample of a compound is decomposed and the masses of its constituent elements is as follows: 1.443 g Se, 0.5848

sladkih [1.3K]

Answer: The empirical formula is $SeO_2$ .

Explanation:

So, the mass of each element is given:

Mass of Se = 1.443 g

Mass of O = 0.5848 g

Step 1 : convert given masses into moles.

Moles of Se= $\frac{\text{ given mass of Se}}{\text{ molar mass of Se}}= \frac{1.443g}{79g/mole}=0.018moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{0.5848g}{16g/mole}=0.036moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For Se = $\frac{0.018}{0.018}=1$

For O = $\frac{0.036}{0.018}=2$

The ratio of Se: O = 1: 2

Hence the empirical formula is $SeO_2$ .

5 0

4 years ago

The energy that plants need for photosynthesis comes from

Deffense [45]

Answer:

OB sunlight

Explanation:

it grows with it

7 0

3 years ago

The molar mass of KCl is 74. 55 g/mol. If 8. 45 g KCl are dissolved in 0. 750 L of solution, what is the molarity of the solutio

rosijanka [135]

Molarity is the strength of the solution or the ratio of the moles and the volume of the solution. The molarity of the solution is 0.1516 mol per Liter.

<h3>What is molarity?</h3>

Molarity is the molar concentration of the solution that tells about the amount of the solute or the substance dissolved in the given amount of the solution.

Given,

Mass of potassium chloride = 8.45 g
Molar mass of potassium chloride = 74. 55 g/mol
Volume of the solution = 0.750 L

Moles can be calculated by:

$\begin{aligned}\rm Moles &= \rm \dfrac{Mass }{\rm Molar \;mass}\\\\&= \dfrac{8.45}{74.55}\\\\&= 0.1133\;\rm mol\end{aligned}$

Calculate molarity by:

$\rm Molarity = \dfrac{moles}{\text{Volume in L}}$

Substituting values in the equation:

$\begin{aligned}\rm Molarity &= \dfrac{0.1133}{0.750}\\\\&= 0.1516 \;\rm mol\;L^{-1}\end{aligned}$

Therefore, the molarity of the solution is 0.1516 mol per Liter.

Learn more about molarity here:

brainly.com/question/2560307

4 0

2 years ago

A chemical reaction with an initial quantity of 1.35 moles of gas is performed in a 4.50-L flask at 24.7°C and under 1.07 atm of

nexus9112 [7]

Answer:

0.488 mol

Explanation:

By the ideal gas law:

PV = nRT

Where P is the pressure, V is the volume, n is the number of moles, R is the gas constant (0.082 atm.L/mol.K), and T is the temperature in K. Thus, after the reaction:

P = 2.92 atm

V = 4.50 L

T = 55.2°C + 273 = 328.2 K

PV = nRT

n = PV/RT

n = (2.92*4.50)/(0.082*328.2)

n = 0.488 mol

8 0

3 years ago