As most substances are cooled they expand true or false

A compound contains 1.2 g of carbon, 3.2 g of oxygen and 0.2g of hydrogen. Find the formula of the compound

Karolina [17]

Answer:

The empirical formula of the compound is $C_{0.504}HO_{1.008}$ .

Explanation:

We need to determine the empirical formula in its simplest form, where hydrogen ( $H$ ) is scaled up to a mole, since it has the molar mass, and both carbon ( $C$ ) and oxygen ( $O$ ) are also scaled up in the same magnitude. The empirical formula is of the form:

$C_{x}HO_{y}$

Where $x$ , $y$ are the number of moles of the carbon and oxygen, respectively.

The scale factor ( $r$ ), no unit, is calculated by the following formula:

$r = \frac{M_{H}}{m_{H}}$ (1)

Where:

$m_{H}$ - Mass of hydrogen, in grams.

$M_{H}$ - Molar mass of hydrogen, in grams per mole.

If we know that $M_{H} = 1.008\,\frac{g}{mol}$ and $m_{H} = 0.2\,g$ , then the scale factor is:

$r = \frac{1.008}{0.2}$

$r = 5.04$

The molar masses of carbon ( $M_{C}$ ) and oxygen ( $M_{O}$ ) are $12.011\,\frac{g}{mol}$ and $15.999\,\frac{g}{mol}$ , then, the respective numbers of moles are: ( $r = 5.04$ , $m_{C} = 1.2\,g$ , $m_{O} = 3.2\,g$ )

Carbon

$n_{C} = \frac{r\cdot m_{C}}{M_{C}}$ (2)

$n_{C} = \frac{(5.04)\cdot (1.2\,g)}{12.011\,\frac{g}{mol} }$

$n_{C} = 0.504\,moles$

Oxygen

$n_{O} = \frac{r\cdot m_{O}}{M_{O}}$ (3)

$n_{O} = \frac{(5.04)\cdot (3.2\,g)}{15.999\,\frac{g}{mol} }$

$n_{O} = 1.008\,moles$

Hence, the empirical formula of the compound is $C_{0.504}HO_{1.008}$ .

3 0

2 years ago

What happens when a catalyst is used in a reaction?.

den301095 [7]

A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy without being used up in the reaction. After the reaction occurs, a catalyst returns to its original state and so catalysts can be used over and over again.

6 0

2 years ago

Under what conditions is the change in internal energy, δe rxn , equal to the heat evolved in a chemical reaction?

Stells [14]

the first law says that the change in internal energy of a system is given by:

δE = δq + δw

where δE is the i change in internal energy, 

δq is the amount of thermal energy added to the system from the surroundings 

δw is the l work done *on* the system *by* the surroundings. 

For a system only undergoing expansion work,
δw = -pδV, so: 

δE = δq - p δV 
when δV = 0, then δe=δq

4 0

3 years ago

Which is the best description of a molecule?

mojhsa [17]

By definition, we have to:
A molecule is a group of at least two atoms in a defined configuration linked by chemical bonds.
We have two types of molecules:
1) several atoms of a single chemical element, as in the case of oxygen. (O2)
2) Atoms of different elements, as in the case of water. (H2O)
Answer:
the best description of a molecule is:
A: A molecule of an element is composed of at least two types of atoms.

3 0

3 years ago

Plate Tectonic Theory is the theory that the world was once 1 continent called Pangea.

irina1246 [14]

Answer:

true

Explanation:

8 0

3 years ago

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