Look at the diagram of a fuel cell below.

A 1.45 g sample of phosphorus burns in air and forms 2.57 g of a phosphorus oxide. Calculate the empirical formula of the oxide.

bija089 [108]

Answer:

P2O3

Explanation:

Firstly, we know that the phosphorus would absorb oxygen from air to form its oxide. We already know the mass of the phosphorus, we can get the mass of the oxygen by subtracting the mass of the phosphorus from the mass of the oxide.

The mass of the oxygen is 2.57 - 1.45 = 1.12g

From here, we covert these masses to moles by dividing by the atomic masses of phosphorus and oxygen respectively.

The atomic mass of phosphorus is 31 while that of oxygen is 16.

P = 1.45/31 = 0.046774193548

O = 1.12/16 = 0.07

We now divide by the smallest which is that of phosphorus.

P = 0.046774193548/ 0.046774193548= 1

O = 0.07/ 0.046774193548 = 1.5

We then multiply the answers by 2 for conversion to whole numbers. Making P = 2 and O = 3

The empirical formula is thus P2O3

5 0

3 years ago

A beaker with 1.60×102 mL of an acetic acid buffer with a pH of 5.000 is sitting on a benchtop. The total molarity of acid and c

stich3 [128]

Answer:

The pH will change 0.16 ( from 5.00 to 4.84)

Explanation:

Step 1: Data given

volume of acetic acid buffer = 160 mL

The total molarity of acid and conjugate base in this buffer is 0.100 M

A student adds 7.10 mL of a 0.460 M HCl solution to the beaker.

The pKa of acetic acid is 4.740

pH = 5.00

Step 2: Calculate concentration of acid

Consider x = concentration acid

Consider y = concentration conjugate base

x + y = 0.100

5.00 = 4.740 + log y/x

5.00 - 4.740 = log y/x

0.26 = log y/x

10^0.26 =1.82 = y/x

1.82 x = y

Since x+y = 0.100

x + 1.82 x = 0.100

2.82 x = 0.100

x =0.0355 M = concentration acid

Step 3: Calculate concentration of conjugate base

y = 0.100 - x

0.100 - 0.0355 =0.0645 M= concentration conjugate base

Step 4: Calculate moles of acid

Moles = volume * molarity

moles acid = 0.160 L * 0.0355 M= 0.00568 moles

Step 5: Calculate moles of conjugate base

moles conjugate base = 0.0645 M * 0.160 L=0.01032 moles

Step 6: Calculate moles HCl

moles HCl = 7.10 * 10^-3 L * 0.460 M=0.003266 moles

Step 7: Calculate new moles

A- + H+ = HA

moles conjugate base = 0.01032 - 0.003266 =0.007054 moles

moles acid = 0.00568 + 0.003266=0.008946 moles

Step 8: Calculate the total volume

total volume = 160 + 7.10 = 167.1 mL = 0.1671 L

Step 9: Calculate the concentration of the acid

concentration acid = 0.008946/ 0.1671 =0.0535 M

Step 10: Calculate the concentration of conjugate base

concentration conjugate base = 0.007054/ 0.1671 =0.0422 M

Step 11: Calculate the pH

pH = 4.740 + log 0.0535/ 0.0422=4.84

change pH = 5.00 - 4.84=0.16

The pH will change 0.16

5 0

2 years ago

How do atoms form new substances?

geniusboy [140]

Atoms combine as the electrons from each atom are attracted to the nuclei of the atoms. This results in bonds ranging from 100% covalent to bonds with high ionic character. The combination of atoms to form compounds occurs when the compounds being formed are at lower energy than the original atoms

5 0

3 years ago

At 100 degrees Celsius, the ion product for pure water is Kw= 51.3*10^-14. What is the pOH of water at this temperature? A) 7.00

Levart [38]

7.86 is the pOH of water at this temperature of 100 degrees celsius.

Option E is the right answer.

Explanation:

Data given:

Kw = 51.3 x $10^{-14}$