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yarga [219]
3 years ago
14

Second time posting this, help asap, please :( Will give a brainliest!

Chemistry
1 answer:
nlexa [21]3 years ago
6 0

Answer:

Reduction half

Fe2+ +2e -------> Fe

Oxidation half

Mn-----> Mn4+. +4e

Explanation:

Oxidation is loss of electron and reduction is gain of electron

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What is moment and its calculations ​
PIT_PIT [208]

Answer:

Moment=Force x Pivot

Explanation:

A moment is the turning effect of a force. Moments act about a point in a clockwise or anticlockwise direction.

Law of moments:

When an object is balanced (in equilibrium) the sum of the clockwise moments is equal to the sum of the anticlockwise moments.

How to calculate moments:

Moment=Force x Pivot

3 0
3 years ago
Mg(OH)2 + 2 HBr à MgBr2 + 2 H2O
AnnyKZ [126]

Explanation:

The balanced equation of the reaction is given as;

Mg(OH)2 (s) + 2 HBr (aq) → MgBr2 (aq) + 2 H2O (l)

1. How many grams of MgBr2 will be produced from 18.3 grams of HBr?

From the reaction;

2 mol of HBr produces 1 mol of  MgBr2

Converting to masses using;

Mass = Number of moles * Molar mass

Molar mass of HBr = 80.91 g/mol

Molar mass of MgBr2 = 184.113 g/mol

This means;

(2 * 80.91 = 161.82g) of HBr produces (1 * 184.113 = 184.113g) MgBr2

18.3g would produce x

161.82 = 184.113

18.3 = x

x = (184.113 * 18.3 ) / 161.82 = 20.8 g

2. How many moles of H2O will be produced from 18.3 grams of HBr?

Converting the mass to mol;

Number of moles = Mass / Molar mass = 18.3 / 80.91 = 0.226 mol

From the reaction;

2 mol of HBr produces 2 mol of H2O

0.226 mol would produce x

2 =2

0.226 = x

x = 0.226 * 2 / 2 = 0.226 mol

3. How many grams of Mg(OH)2 are needed to completely react with 18.3 grams of HBr?

From the reaction;

2 mol of HBr reacts with 1 mol of Mg(OH)2

18.3g of HBr =  0.226 mol

2 = 1

0.226 = x

x = 0.226 * 1 /2

x = 0.113 mol

5 0
3 years ago
Calculate the amount of time required to raise temperature of 0.50 liter of water from
Burka [1]
<h3>Answer:</h3>

19 seconds

<h3>Explanation:</h3>

Heat energy was supplied and used to heat 0.50 liters of water from 0°C to 10°C.

This means water gained heat energy that was supplied.

Therefore;

Heat supplied = Heat gained by water

We are required to calculate the time taken to raise the temperature of water from 0°C to 10°C.

Step 1: Calculate the heat gained by water

Quantity of heat = Mass × specific heat capacity × change in temperature

Density of water 1 g/ml

Volume of water is 500 mL

Therefore, since Mass = density × volume

The mass of water = 500 g

Change in temperature = 10° C

Specific heat capacity of water = 4.18 J/g/°C

Thus;

Quantity of heat = 500 g × 4.18 J/g/°C × 10

                           = 20,900 Joules

Step 2: Heat supplied by a heater

Heat supplied = Power × time

Power = 1100 J/s

Assuming the time required is x

Heat supplied = 1100x Joules

Step 3: Time required

Remember; heat supplied = heat gained by water

Therefore;

1100x joules = 20,900 Joules

      x = 20,900/1100

        = 19 seconds

Therefore, the time required to raise the temperature of water from 0°C to 10°C is 19 seconds.

6 0
3 years ago
Rank the compounds NH3, CH4, and PH3 in order of decreasing boiling point. Choices: A) NH3 &gt; CH4 &gt; PH3 B) CH4 &gt; NH3 &gt
Andre45 [30]

Answer:

C) NH3 > PH3 > CH4

Explanation:

The boiling point of a substance depends on the nature of intermolecular interaction between the molecules of the substance. The greater the magnitude of intermolecular interaction between the molecules of the substance, the higher the boiling point of the substance.

Both NH3 and PH3 have intermolecular hydrogen bonding between their molecules. However, since nitrogen is more electronegative than phosphorus, the magnitude of intermolecular hydrogen bonding in NH3 is greater than in PH3 hence NH3 has a higher boiling point than PH3.

CH4 molecules only have weak dispersion forces between them hence they exhibit the lowest boiling point.

7 0
3 years ago
The combustion of propane may be described by the chemical equation C 3 H 8 ( g ) + 5 O 2 ( g ) ⟶ 3 CO 2 ( g ) + 4 H 2 O ( g ) C
Kipish [7]

Answer: 72 grams of O_2(g) are needed to completely burn 19.7 g C_3H_8(g)

Explanation:

According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number 6.023\times 10^{23} of particles.

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

Putting in the values we get:

\text{Number of moles}=\frac{19.7g}{44g/mol}=0.45moles

C_3H_8(g)+5O_2(g)\rightarrow 3CO_2(g)+4H_2O(g)

According to stoichiometry:

1 mole of C_3H_8 requires 5 moles of oxygen

0.45 moles of C_3H_8 require= \frac{5}{1}\times 0.45=2.25 moles of oxygen

Mass of O_2=moles\times {\text {Molar mass}}=2.25\times 32=72g

72 grams of O_2(g) are needed to completely burn 19.7 g C_3H_8(g)

7 0
3 years ago
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