Oxygen, hydrogen, and water are substances. which of these substances are elements

Melatonin has the chemical formula C13H16N2O2. Less than 10 milligrams(0.01g) Convert the melatonin to moles

oee [108]

Answer: There are 0.000043 moles of melatonin.

Explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number $6.023\times 10^{23}$ of particles.

To calculate the moles, we use the equation:

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

given mass = 10 mg = 0.01 g

molar mass of $C_{13}H_{16}N_2O_2$ = 232.28 g

${\text {moles of melatonin}}=\frac{0.01g}{232.28g/mol}=0.000043moles$

Thus there are 0.000043 moles of melatonin

6 0

2 years ago

Use the reaction given below to solve the problem that follows: Calculate the mass in grams of aluminum oxide produced by the re

bearhunter [10]

Answer: 28.4 g of aluminum oxide is produced by the reaction of 15.0 g of aluminum metal

Explanation:

To calculate the moles :

$\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}$

$\text{Moles of} Al=\frac{15.0g}{27g/mol}=0.556moles$

The balanced chemical equuation is:

$4Al+3O_2\rightarrow 2Al_2O_3$

According to stoichiometry :

4 moles of $Al$ produce == 2 moles of $Al_2O_3$

Thus 0.556 moles of $Al$ will produce= $\frac{2}{4}\times 0.556=0.278moles$ of $Al_2O_3$

Mass of $Al_2O_3=moles\times {\text {Molar mass}}=0.278moles\times 102g/mol=28.4g$

Thus 28.4 g of aluminum oxide is produced by the reaction of 15.0 g of aluminum metal.

7 0

2 years ago

EIGHTY POINTS- WILL GET BRAINLIEST NEED ANSWER ASAP

il63 [147K]

ans A. 13 to 3

solution:

Total puppies for sale=6

Total puppies left = 2

hence total puppies sold= 6 - 2 = 4

cost of a puppy= $ 104

so cost of 2 puppies = 104 x 4

=416$

Now for kittens:

Total kittens for sale = 12

Total kittens left = 8

hence total kittens sold=12 - 8 =4

cost of a kitten = $24

so cost of 4 kittens= 24x 4=96$

Now ratio of sales of puppies to kittens = 208$/96$

= 13/3 or 13:3 or 13 to 3

I hope this explanation will help you to understand this problem

5 0

2 years ago

A sample of a compound is decomposed in the laboratory and produces 330 g carbon, 69.5 g hydrogen, and 220.2 g oxygen. Calculate

Zarrin [17]

Answer: Empirical formula is $C_2H_5O$

Explanation: We are given the masses of elements present in a sample of compound. To evaluate empirical formula, we will be following some steps.

Step 1 : Converting each of the given masses into their moles by dividing them by Molar masses.

$Moles=\frac{\text{Given mass}}{\text{Molar mass}}$

Molar mass of Carbon = 12.0 g/mol

Molar mass of Hydrogen = 1.0 g/mol

Molar mass of Oxygen = 16.0 g/mol

Moles of Carbon = $\frac{330g}{12g/mol}=27.5moles$

Moles of Hydrogen = $\frac{69.5g}{1g/mol}=69.5moles$

Moles of Oxygen = $\frac{220.2g}{16g/mol}=13.76moles$

Step 2: Dividing each mole value by the smallest number of moles calculated above and rounding it off to the nearest whole number value

Smallest number of moles = 13.76 moles

$\text{Mole ratio of Carbon}=\frac{27.5moles}{13.76moles}=1.99\approx 2$

$\text{Mole ratio of Hydrogen}=\frac{69.5moles}{13.76moles}=5.05\approx 5$

$\text{Mole ratio of Oxygen}=\frac{13.76moles}{13.76moles}=1$

Step 3: Now, the moles ratio of the elements are represented by the subscripts in the empirical formula

Empirical formula becomes = $C_2H_5O$

7 0

2 years ago

What are each symbiotic relationships? Help please:))

Fudgin [204]

Answer:

commensalism, mutualism, parasitism

4 0

2 years ago