All categories

3 years ago

How is a pure substance different from other substances?

Chemistry

1 answer:

iren [92.7K]3 years ago

7 0

Answer:

Explanation:

A pure substance is made up solely of that substance and can't be separated into any other substances. A mixture can be separated into two or more pure substances

You might be interested in

A buffer with a pH of 3.98 contains 0.23 M of sodium benzoate and 0.38 M of benzoic acid. What is the concentration of [H3O+] in

Vika [28.1K]

Answer:

New pH = 3.84

Explanation:

First of all we may think that if the buffer has pH 3.98 and we're adding H⁺, pH's buffer will be lower, as the [H⁺] is been increased.

Let's determine the moles of each compound:

0.23 M . 1.3L = 0.299 moles of NaBz

0.38 M . 1.3L = 0.494 moles of HBz

We add 0.058 of HCl, which is the same as 0.058 moles of H⁻

HCl → H⁺ + Cl⁻

As we add the moles of protons, these are going to react to the Bz⁻

In the buffer system we have these dissociations:

NaBz → Na⁺ + Bz⁻

HBz → H⁺ + Bz⁻

So, as we add protons, we have a new equilibrium:

Bz⁻ + H⁺ ⇄ HBz

In 0.299 0.058 0.494

Eq 0.241 - 0.552

Protons are substracted to benzoate, so the [HBz] is now higher than before. We calculate the new pH, with the Henderson Hasselbach equation

pH = pKa + log (Bz⁻/HBz)

pH = 4.20 + log (0.241 / 0.552) → 3.84

3 0

3 years ago

100 POINTS!!!

mixas84 [53]

1) Area of one side of each cube

The area of one side of each cube can be calculated by multiplying the length times the width:

$A=L\cdot W$

where

L = length

W = width

For cube A: $L=1 cm, W=1 cm$

So the area is: $A_A = (1)(1)=1 cm^2$

For cube B: $L=2 cm, W=2 cm$

So the area is: $A_B=(2)(2)=4 cm^2$

For cube C: $L=3 cm, W=3 cm$

So the area is: $A_C=(3)(3)=9 cm^2$

2) Surface area of each cube

The surface area of a cube is given by the sum of the areas of all its faces. Since a cube has 6 identical faces, this means that the total surface area is equal to 6 times the area of one face:

$A=6 A_1$