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2 years ago

How many moles of oxygen do you need to burn one mole of Mg?

Chemistry

1 answer:

kenny6666 [7]2 years ago

4 0

Answer:

You need 0.5 moles of oxygen to burn one mole of Mg.

Explanation:

The balanced reaction is:

2 Mg + O₂ → 2 MgO

When chemical changes occur, the chemical elements are conserved, so the number of atoms is the same before and after the change. To represent this equality of the number of atoms, the expression is "balanced" or "equalized". That's why you put a two in front of the magnesium formula and a two in front of the magnesium oxide to equal the number of atoms involved in the change. These numbers used are called stoichiometric coefficients. The stoichiometric coefficients allow to establish the molar ratio in which the reactants combine and the products are formed.

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction) the following amounts of each compound participate in the reaction:

Mg: 2 moles
O₂: 1 mole
MgO: 2 moles

Then you can apply the following rule of three: if by reaction stoichiometry 2 moles of magnesium reacts with , 1 mole of magnesium reacts with how many moles of oxygen?

$amount of moles of oxygen=\frac{ 1 mole of magnesium*1 mole of oxygen}{ 2 moles of magnesium}$

amount of moles of oxygen= 0.5 moles

You need 0.5 moles of oxygen to burn one mole of Mg.

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A shiny chunk of metal is found to have a mass of 37.28g. The metal is dropped into a graduated cylinder which contains 20.0 mL

Amanda [17]

Answer: The density of the material is 2.66 g/mL and it is likely this is made of Aluminum

Explanation:

The first step to know the material of the chunk of metal is to calculate its density. The general formula for density is P (density) = $\frac{m (mass)}{ v (volume)}$ . Moreover, in this case, it is known the mass is 37.28 g, but the volume is not directly provided. However, we know the water in the graduated cylinder had a volume of 20.0 mL and this increased to 34.0 mL when the chunk of metal is added, this means the volume of the metal is 14 mL (34.0 mL - 20.0 mL = 14 mL). Now let's calculate the density:

$P =$ $\frac{37.28g}{14.0mL}$

$P = 2.66 g/mL$

This means the density of this metal is 2.66 g/mL, which can be rounded as 2. 7 g/mL, and according to the chart, this is the density of aluminum. Therefore, this material of this chunk is aluminum.

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3 years ago

The melting point of aluminum is about 660 °C. How many degrees above the boiling point of water is this temperature?

Arte-miy333 [17]

560 degrees above water

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2 years ago

What is the volume of a substance that has a density of 13.6 g/cm and a mass of 3.0 g?

MakcuM [25]

Answer:

$\boxed {\boxed {\sf v \approx 0.22 \ cm^3}}$

Explanation:

We are asked to find the volume of a substance.

We are given the density and the mass. The density of a substance is its mass per unit volume. The formula for calculating density is:

$\rho= \frac{m}{v}$

We know the density of the substance is 13.6 grams per cubic centimeter and the mass is 3.0 grams.

ρ= 13.6 g/cm³
m= 3.0 g

Substitute these values into the formula.

$13.6 \ g/cm^3= \frac{3.0 \ g }{v}$

We are solving for the volume, so we must isolate the variable v. First, cross multiply. Multiply the first numerator by the second denominator, then multiply the first denominator by the second numerator.

$\frac{13.6 \ g/cm^3}{1}= \frac{3.0 \ g }{v}$

$13.6 \ g/cm^3 *v =3.0 \ g *1$

Multiply on the right side of the equation.

$13.6 \ g/cm^3 *v =3.0 \ g$

The variable is being multiplied by 13.6 grams per cubic centimeters. The inverse operation of multiplication is division, so we divide both sides of the equation by 13.6 g/cm².

$\frac {13.6 \ g/cm^3 *v}{13.6 \ g/cm^3} =\frac{3.0 \ g }{13.6 \ g/cm^3}$

$v =\frac{3.0 \ g }{13.6 \ g/cm^3}$

The units of grams cancel.

$v =\frac{3.0 }{13.6 \ cm^3}$

$v= 0.2205882353 \ cm^3$

The original measurement of density has 3 significant figures and the measurement of mass has 2. Our answer must have the least number of sig figs, which is 2. For the number we found, that is the hundredth place. The 0 in the thousandth place tells us to leave the 2 in the hundredth place.

$v \approx 0.22 \ cm^3$

The volume of the substance is approximately 0.22 cubic centimeters.

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2 years ago

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kicyunya [14]

Answer: Option B

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This kind of a membrane is known as selectively permeable which allows the movement of certain molecules only.

hence, the correct answer is option B

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