Pls help . I don't know this one .

How many seconds are in 5 hours

vfiekz [6]

18000 seconds = 5 hours

8 0

2 years ago

Read 2 more answers

Write the atomic symbol for the isotope of bismuth with 125 neutrons.

vlada-n [284]

First, isotopes are the atoms of a single element whose nuclei have a different number of neutrons, and therefore, differ in mass numbers. You should know that atoms are formed by a nucleus that has a small size and is made up of protons and neutrons. The nucleus is surrounded by a cloud of electrons, which are found in a region of the atom called the cortex.

The mass number, represented as A, is the sum of the number of protons and neutrons in the nucleus. On the other hand, the atomic number (Z) is the number of protons that exist in the nucleus.

The isotopes of an element X are represented as follows,

(see first attached picture)

It should be noted that the number of neutrons of a chemical element can be calculated as the difference A-Z.

The atomic and mass numbers of bismuth with 125 neutrons are:

Z = 83

A = 83 + 125 = 208

Thus, the atomic symbol of the bismuth isotope with 125 neutrons is:

(see second attached picture)

5 0

2 years ago

Aspirin can be prepared from salicylic acid ( C 7 H 6 O 3 CX7HX6OX3), which has a molar mass of 138.12 g/mol, and acetic anhydri

pychu [463]

Answer: The theoretical yield of aspirin is 4.14 g

Explanation:

To calculate the moles :

$\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}$ $\text{Moles of salicylic acid}=\frac{3.20g}{138.12g/mol}=0.023moles$

mass of acetic anhydride = $density\times volume =1.082g/ml\times 3.71ml=4.01g$

$\text{Moles of acetic anhydride}=\frac{4.01g}{102.04g/mol}=0.039moles$

$C_9H_6O_3+C_4H_6O_3\rightarrow C_9H_8O_4+C_2H_3O_2$

According to stoichiometry :

1 mole of salycylic acid require 1 mole of acetic anhydride

Thus 0.023 moles of salycylic acid require= $\frac{1}{1}\times 0.023=0.023moles$ of acetic anhydride

Thus salycylic acid is the limiting reagent as it limits the formation of product and acetic anhydride is the excess reagent.

As 1 mole of salycylic give = 1 mole of aspirin

Thus 0.023 moles of salycylic acid give = $\frac{1}{1}\times 0.023=0.023moles$ of aspirin

Mass of aspirin = $moles\times {\text {Molar mass}}=0.023moles\times 180.15g/mol=4.14g$

Thus theoretical yield of aspirin is 4.14 g

4 0

3 years ago

Can someone help me?

Natalka [10]

Answer 19.9g. I’ve took the test last week at my uncle randy’s house

8 0

3 years ago

"which is a correct description of the organization of subatomic particles in atoms?"

Irina18 [472]

Which is a correct description of the organization of subatomic particles in atoms?

Protons and neutrons are tightly packed into a small nucleus. Electrons occupy the space
outside the nucleus

hope this helps.

5 0

2 years ago