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Vikentia [17]
2 years ago
9

An unknown element X has the following isotopes: ²⁵X (80.5% abundant) and ²⁷X (19.5% abundant). What is the average atomic mass

in amu of X?
Chemistry
1 answer:
IgorC [24]2 years ago
5 0

Answer:

25.39

Explanation:

Given parameters:

Abundance of X-25  = 80.5%

Abundance of X - 27  = 19.5%

Unknown:

Average atomic mass of X  = ?

Solution:

The average atomic mass of X can be derived using the expression below:

Average atomic mass = (abundance x mass of X - 25) + (abundance x mass of X - 27)

Average atomic mass  =  (80.5%  x 25) +   (19.5% x 27)  = 25.39

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A 32.5 g piece of aluminum (which has a specific heat capacity of 0.921 J/g°C) is heated to 82.4°C and dropped into a calorimete
N76 [4]

Answer:

The mass of water = 219.1 grams

Explanation:

Step 1: Data given

Mass of aluminium = 32.5 grams

specific heat capacity aluminium = 0.921 J/g°C

Temperature = 82.4 °C

Temperature of water = 22.3 °C

The final temperature = 24.2 °C

Step 2: Calculate the mass of water

Heat lost = heat gained

Qlost = -Qgained

Qaluminium = -Qwater

Q = m*c*ΔT

m(aluminium)*c(aluminium)*ΔT(aluminium) = -m(water)*c(water)*ΔT(water)

⇒with m(aluminium) = the mass of aluminium = 32.5 grams

⇒with c(aluminium) = the specific heat of aluminium = 0.921 J/g°C

⇒with ΔT(aluminium) = the change of temperature of aluminium = 24.2 °C - 82.4 °C =  -58.2 °C

⇒with m(water) = the mass of water = TO BE DETERMINED

⇒with c(water) = 4.184 J/g°C

⇒with ΔT(water) = the change of temperature of water = 24.2 °C - 22.3 °C = 1.9 °C

32.5 * 0.921 * -58.2 = -m * 4.184 * 1.9

-1742.1 = -7.95m

m = 219.1 grams

The mass of water = 219.1 grams

8 0
2 years ago
5.00 g of hydrogen gas and 50.0g of oxygen gas are introduced into an otherwise empty 9.00L steel cylinder, and the hydrogen is
GenaCL600 [577]
1) Balanced chemical reaction:

2H2 + O2 -> 2H20

Sotoichiometry: 2 moles H2: 1 mol O2 : 2 moles H2O

2) Reactant quantities converted to moles

H2: 5.00 g / 2 g/mol = 2.5 mol

O2: 50.0 g / 32 g/mol = 1.5625 mol

Limitant reactant: H2 (because as per the stoichiometry it will be consumed with 1.25 mol of O2).

3) Products

H2 totally consumed -> 0 mol at the end

O2 = 1.25 mol consumed -> 1.5625 mol - 1.25 mol = 0.3125 mol at the end

H2O: 2.5 mol H2 produces 2.5 mol H2O -> 2.5 mol at the end.

Total number of moles: 0.3125mol + 2.5 mol = 2.8125 mol

4) Pressure

Use pV = nRT
n = 2.8125
V= 9 liters
R = 0.082 atm*lit/K*mol
T = 35 C + 273.15 = 308.15K

p = nRT/V  = 7.9 atm
3 0
2 years ago
Read 2 more answers
Athletic trainers use instant ice packs that can be cooled quickly on demand. Squeezing the pack breaks an inner container, allo
MrMuchimi

Answer:

The heat flow is  best described as an exchange of heat between the system and the surroundings.

Explanation:

Heat is a form of energy which is transferred spontaneously from a hotter body to a cool body as a result of temperature differences between the substances. In the problem , it can be said that heat moves from  the surroundings which may be a fractured knee of the athlete to the ice packs.  

7 0
2 years ago
Heavy nuclides with too few neutrons to be in the band of stability are most likely to decay by what mode?
Margarita [4]

Answer:

Positron emission

Explanation:

Positron emission involves the conversion of a proton to a neutron. This process increases the mass number of the daughter nucleus by 1 while its atomic number remains the same. The new neutron increases the number of neutrons present in the daughter nucleus hence the process increases the N/P ratio.

A positron is usually ejected in the process together with an anti-neutrino to balance the spins.

6 0
2 years ago
Synthesis of disubstituted benzenes involves two steps, each introducing one of the functional groups. For the synthesis of p-ch
Setler79 [48]

Answer:

The synthesis of p-chlorobenzenesulfonic acid with the reagents for each step and the structure of the monosubstituted intermediate compound is shown in the drawing below.

Explanation:

Benzenesulfonic acid is obtained from the sulfonation of benzene, using concentrated smoking sulfuric acid.

Chlorination of benzenesulfonic acid with chlorine without catalyst requires a polar solvent, such as acetic acid to obtain the selectivity in the position for and the ortho derivative in a low proportion.

7 0
2 years ago
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