plz help me asap (plz don't give me helpless answer plz and ty) and also ill give brainist to the person that work hard

Chemistry

1 answer:

Vesna [10]2 years ago

8 0

Question? I don’t see anything

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What mass of Na2SO4 is needed to make 2.5L of 2.0 M solution?

Gala2k [10]

Moles of Na2SO4 = conc. x volume(dm3)
= 2 x (2500cm3/1000)
= 5 mol

Mass of Na2SO4 = moles x molar mass
= 5 x ((23 x 2) + 32.1 + (16 x 4))
= 710.5g

5 0

3 years ago

kondor19780726 [428]

Explanation:

It is known that 1 gram contains 1000 milligrams. And, mathematically we can represent it as follows.

$\frac{1 g}{1000 mg}$ or $\frac{1000 mg}{1 g}$

So, when we have to convert grams into milligrams then we simply multiply the digit with 1000. And, if we have to convert a digit from milligrams to grams then we simply divide it by 1000.

4 0

3 years ago

A ground state hydrogen atom absorbs a photon of light having a wavelength of 92.05 nm. It then gives off a photon having a wave

vodka [1.7K]

Absorbed photon energy
Ea = hc/λ.. (Planck's equation)
Ea = hc / 92.05^-9m

<span>Energy emitted
Ee = hc/ 1736^-9m </span>

Energy retained ..
∆E = Ea - Ee = hc(1/92.05<span>^-9 - 1/1736^-9) </span>
<span>∆E = (6.625^-34)(3.0^8) (1.028^7)
∆E = 2.04^-18 J </span>

<span>Converting J to eV (1.60^-19 J/eV)
∆E = 2.04^-18 / 1.60^-19
∆E = 12.70 eV </span>

<span>Ground state (n=1) energy for Hydrogen = - 13.60eV </span>

<span>New energy state = (-13.60 + 12.70)eV = -0.85 eV </span>

<span>Energy states for Hydrogen
En = - (13.60 / n²) </span>

n² = -13.60 / -0.85 = 16
n = 4

4 0

3 years ago

You have a graduated cylinder with 10 mL of water in it.

Law Incorporation [45]

Answer:

<h3>The answer is 10 g/mL</h3>

Explanation:

The density of a substance can be found by using the formula

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