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2 years ago

The positive sign of the energy difference in a chemical reaction would indicate that ..........

Chemistry

1 answer:

trasher [3.6K]2 years ago

3 0

Answer:

B) the chemicals are gaining energy from the surroundings.

Explanation:

The positive sign of the energy difference in a chemical reaction would indicate that the chemicals are gaining energy from the surroundings. This is what happens in an endothermic reaction.

In an endothermic reaction, heat is absorbed from the surroundings hence the surrounding becomes colder at the end of the changes.

Here the energy change is assigned a positive value.
This is because the heat energy level of the final state is higher than that of the initial state.
So, the difference gives a positive value.

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If you have a density of 100 kg/L and a mass of 1000 g what is the volume (please explain)

olchik [2.2K]

Answer: Volume = 0.01L

Explanation:

The density of a substance is given by; Density = Mass / Volume.

In this question, Mass = 1000g, Volume = ? and Density = 100 Kg/L

For the units to be uniform, we convert 1000g to Kg = 1Kg

Therefore, Volume = Mass / Density = 1Kg / 100Kg/L = 0.01L

6 0

3 years ago

During a synthesis reaction, 1.8 grams of magnesium reacted with 6.0 grams of oxygen. What is the maximum amount of magnesium ox

skelet666 [1.2K]

Answer:

2.9 grams.

Explanation:

From the balanced reaction:

Mg + 1/2O₂ → MgO,

1.0 mole of Mg reacts with 0.5 mole of oxygen to produce 1.0 mole of MgO.

We need to calculate the no. of moles of (1.8 g) of Mg and (6.0 g) of oxygen:

no. of moles of Mg = mass/molar mass = (1.8 g)/(24.3 g/mol) = 0.074 mol.

no. of moles of O₂ = mass/molar mass = (6.0 g)/(16.0 g/mol) = 0.375 mol.

So. 0.074 mol of Mg reacts completely with (0.074/2 = 0.037 mol) of O₂ which be in excess.

Using cross multiplication:

1.0 mole of Mg produce → 1.0 mol of MgO.

∴ 0.074 mol of Mg produce → 0.074 mol of MgO.

∴ The amount of MgO produced = no. of moles x molar mass = (0.074 mol)(40.3 g/mol) = 2.98 g.

5 0

3 years ago

20.0 g of bromic acid, HBrO3, is reacted with excess HBr.

Blababa [14]

After Rounding off The percentage yield is 64%

<h3>What is Percentage Yield ?</h3>

It is the ratio of actual yield to theoretical yield multiplied by 100% .

It is given in the question

20.0 g of bromic acid, HBrO3, is reacted with excess HBr.

The reaction is

HBrO₃ (aq) + 5 HBr (aq) → 3 H₂O (l) + 3 Br₂ (aq)

Actual yield = 47.3 grams

Molecular weight of Bromic Acid is 128.91 gram

Moles of Bromic Acid = 20/128.91 = 0.155 mole

Mole fraction ratio of Bromic Acid to Bromine is 1 :3

Therefore for 0.155 mole of Bromic Acid 3 * 0.155 = 0.465 mole of Bromine is produced.

1 mole of Bromine = 159.8 grams of Bromine

0.465 of Bromine = 74.31 grams of Bromine

Percentage Yield = (47.3/74.31)*100 = 63.65 %

After Rounding off The percentage yield is 64% .

To know more about Percentage Yield

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5 0

1 year ago

Heat flows naturally from objects that have higher energy to those with?

Vlad [161]

Answer:

heat flow

Explanation:

heat flow moves to a higher temperature to a lower temperature

8 0

2 years ago

Which element has the greatest density at STP?

son4ous [18]

Answer: Option (4) is the correct answer.

Explanation:

It is known that density is mass divided by volume.

Mathematically, Density = $\frac{mass}{volume}$

Since, density is directly proportional to mass. So, more is the mass of an element more will be its density.

Mass of magnesium is 24.305 g/mol.

Mass of barium is 137.327 g/mol.

Mass of beryllium is 9.012 g/mol

Mass of radium is 226 g/mol.

Hence, radium has more mass therefore it will have the greatest density at STP.

8 0

3 years ago