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4 years ago

In the reaction 2Mg (s) + O2 (g) + 2H2O (l) → 2Mg2+ (aq) + 4OH– (aq), which substance is reduced?

Chemistry

1 answer:

Bogdan [553]4 years ago

6 0

F. None of the above

No O atoms are present as reacting substances, only O_2 and H_2O molecules.

O_2 + 2H_2O + 2e^(-) → 4OH^(-)

We must use oxidation numbers to decide whether oxygen or water is the substance reduced.

The oxidation number of O changes from 0 in O_2 to -2 in OH^(-).

A decrease in oxidation number is reduction, so O_2 is the substance reduced.

The oxidation number of O is -2 in both H_2O and OH^(-), so water is neither oxidized nor reduced.

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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

aseous methane will react with gaseous oxygen to produce gaseous carbon dioxide and gaseous water . Suppose 5.5 g of methane is

maksim [4K]

Answer:

There is 9.6 grams of CO2 produced

Explanation:

Step 1: Data given

Mass of methane = 5.50 grams

Molar mass of methane = 16.04 g/mol

Mass of oxygen = 13.9 grams

Molar mass of oxygen = 32.0 g/mol

Step 2: The reaction

CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)

Step 3: Calculate number of moles

Moles = mass / molar mass

Moles methane = 5.50 grams / 16.04 g/mol

Moles methane = 0.343 moles

Moles oxygen = 13.9 grams / 32.0 g/mol

Moles oxygen = 0.434 moles

For 1 mol CH4 we need 2 moles O2 to produce 1 mol CO2 and 2 moles H2O

O2 is the limiting reactant. It will completely react (0.434 moles).

There will react 0.434/2 = 0.217 moles CH4

There will remain 0.343-0.217 = 0.126 moles CH4

There will be produced 0.434 moles of H2O and

0.434/2 =0.217 moles of CO2

Step 4: Calculate mass of products

Mass = moles * molar mass

Mass CO2 = 0.217 moles ¨44.01 g/mol

Mass CO2 = 9.6 grams

Mass H2O = 0.434 moles * 18.02

Mass H2O = 7.8 grams

4 0

3 years ago

An atom has an average atomic mass of about 63.5 amu. What is the chemical symbol for the atom? Consult the periodic table.

Mama L [17]

The best and most correct answer among the choices provided by your question is the fourth choice.

Copper has an average atomic mass of about 63.5 amu.

I hope my answer has come to your help. Thank you for posting your question here in Brainly. We hope to answer more of your questions and inquiries soon. Have a nice day ahead!

8 0

4 years ago

Read 2 more answers

Before you start an investigation, you see the Hazard symbol for Electrical Hazard. What safety steps should you follow when con

Fantom [35]

Explanation:

Safety hazards means they are are the unsafe working conditions which can cause the workmen injury, illness, or death. Safety hazards are some of the most common risks at the workplace.

Electrical hazards may be defined as a place or a condition which is dangerous and where a person working can come in contact with electrical contact with some energized equipment or any electrical conductor. There is always danger or a chance for the workmen to get injury or get a flash burn while working.

The safety steps are :

1. Follow the instruction properly

2. Take proper safety measures like wearing gloves, shoes, not touching any live wires, etc.

3. Follow the clean up procedure properly.

7 0

3 years ago

Un medicamento corresponde a una disolución de "nafazolina" (sustancia activa) en agua purificada, en una concentración de 12% V

ratelena [41]

Answer:

12 mL

Explanation:

Según la pregunta;

V / V% concentración del fármaco = 12%

volumen de la solución = 100 ml

De;

V / V% = volumen de fármaco / volumen de solución

volumen de fármaco = V / V% × volumen de solución

volumen de fármaco = 12/100 × 100

= 12 mL

5 0

3 years ago