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3 years ago

Classify matter as elements mixtures and compounds

Chemistry

1 answer:

Goryan [66]3 years ago

5 0

Answer:

An element contains just one type of atom. A compound contains two or more different atoms joined together. A mixture contains two or more different substances that are only physically joined together, not chemically. A mixture can contain both elements and compounds.

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A solution contains [Ba2+] = 5.0 × 10−5 M, [Zn2+] = 2.0 × 10−7 M, and [Ag+] = 3.0 × 10−5 M. Sodium oxalate (Na2C2O4) is slowly a

Jet001 [13]

Answer:

BaC₂O₄, then ZnC₂O₄, then Ag₂C₂O₄

Explanation:

1. Calculate the equilibrium concentrations of oxalate ion

Let [C₂O₄²⁻] = c

(a) Barium oxalate

BaC₂O₄ ⇌ Ba²⁺ + C₂O₄²⁻

E/mol·L⁻¹: 5.0 × 10⁻⁵ c

Ksp = [Ba²⁺][C₂O₄²⁻] = 5.0 × 10⁻⁵c = 1.5 × 10⁻⁸

c = (1.5 × 10⁻⁸)/(5.0 × 10⁻⁵) = 3.0 × 10⁻⁴ mol·L⁻¹

(b) Zinc oxalate

ZnC₂O₄ ⇌ Zn²⁺ + C₂O₄²⁻

E/mol·L⁻¹: 2.0 × 10⁻⁷ c

Ksp = [Zn²⁺][C₂O₄²⁻] = 2.0 × 10⁻⁷c = 1.35 × 10⁻⁹

c = (1.35 × 10⁻⁹)/(2.0 × 10⁻⁷) = 6.8 × 10⁻³ mol·L⁻¹

(c) Silver oxalate

Ag₂C₂O₄ ⇌ 2Ag⁺ + C₂O₄²⁻

E/mol·L⁻¹: 3.0 × 10⁻⁵ c

Ksp = [Ag⁺]²[C₂O₄²⁻] = (3.0× 10⁻⁵)²c = 9.0 × 10⁻¹⁰c = 1.1 × 10⁻¹¹

c = (1.1 × 10⁻¹¹)/(9.0 × 10⁻¹⁰) = 0.012 mol·L⁻¹

2. Decide the order of precipitation

BaC₂O₄ will precipitate when c > 3.0 × 10⁻⁴ mol·L⁻¹

ZnC₂O₄ will precipitate when c > 6.8 × 10⁻³ mol·L⁻¹

Ag₂C₂O₄ will precipitate when c > 0.028 mol·L⁻¹

This happens to be the order of increasing concentration of oxalate ion.

The order of precipitation is

BaC₂O₄, then ZnC₂O₄, then Ag₂C₂O₄

4 0

3 years ago

For all of the following questions 20.00 mL of 0.200 M HBr is titrated with 0.200 M KOH.

HACTEHA [7]

Answer :

The concentration of $H^+$ before any titrant added to our starting material is 0.200 M.

The pH based on this $H^+$ ion concentration is 0.698

Explanation :

First we have to calculate the concentration of $H^+$ before any titrant is added to our starting material.

As we are given:

Concentration of HBr = 0.200 M

As we know that the HBr is a strong acid that dissociates complete to give hydrogen ion $H^+$ and bromide ion $Br^-$ .

As, 1 M of HBr dissociates to give 1 M of $H^+$

So, 0.200 M of HBr dissociates to give 0.200 M of $H^+$

Thus, the concentration of $H^+$ before any titrant added to our starting material is 0.200 M.

Now we have to calculate the pH based on this $H^+$ ion concentration.

pH : It is defined as the negative logarithm of hydrogen ion concentration.

$pH=-\log [H^+]$

$pH=-\log (0.200)$

$pH=0.698$

Thus, the pH based on this $H^+$ ion concentration is 0.698

3 0

3 years ago

If the mass of an object is 60.0 grams and the density of the object is 15.0 g/mL, what is the volume of the object? The formula

laila [671]

Answer:

168.56 mL

Explanation:

density = mass/volume, use basic algebra skills to replace the volume and solve

7 0

2 years ago

Corn plants may be tall (TT or Tt) or short (tt). The breeding of two parent corn plants results in offspring that are all tall.

zubka84 [21]

Answer:

Explanation:

The probability that both of the parents are homozygous recessive is zero.
In our case, The gene for tallness is dominant over the gene for dwarfism
Therefore; TT is homozygous dominant while tt is homozygous recessive and Tt is heterozygous.
Heterozygous genotype (Tt) will exhibit a tall phenotype.
When two parents are crossed and all the offsprings are tall then the possible genotype of the parents is either;

Homozygous dominant for both parents or

TT x TT

2. One parent is homozygous dominant and the other is homozygous recessive.

TT x Tt

Therefore, the probability of having both parents as homozygous recessive when all the offspring are tall is Zero.

8 0

3 years ago

Briefly describe how a potentiometric pHmeter works. (Hint: Describe how the pH meter

cupoosta [38]

Answer:

A potentiometric pH meter is used to measure the pH of a solution.

Explanation:

A pH meter is an common instrument that is used to measure the hydrogen-ion concentration in aqueous solutions , the meter indicates its acidity or alkalinity and is expressed as pH.

The pH meter measures the difference in electrical potential between a pH electrode and a reference electrode, hence the pH meter is often called a potentiometric pH meter. The difference in electrical potential is related to the pH of the solution.

Potentiometric pH meters consists of a simple electronic amplifier and a pair of electrodes, alternatively it may consist of a combination electrode, and some form of display calibrated in pH units. It usually has a glass electrode and a reference electrode, or a combination electrode. The electrodes, or probes, are inserted into the solution to be tested and pH values are read off.

5 0

3 years ago