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3 years ago

Write the symbol for every chemical element that has atomic number less than 75 and atomic mass greater than 173.5 u.

1 answer:

8 0

Following are the chemical elements that have atomic mass greater than 173.5 u and atomic number less than 75.

1. Lutetium
Atomic Number = 71
Atomic Mass = 174.97 u

2. Hafnium
Atomic Number = 72
Atomic Mass = 178.49 u

3. Tantalum
Atomic Number = 73
Atomic Mass = 180.95 u

4. Tungsten
Atomic Number = 74
Atomic Mass = 183.85 u

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The molar madd of Ca(OH)2

Nonamiya [84]

What you have to do is find a periodic table and add the mass of each atom that the compound is made of.

Ca= 40.1
O= 16.0
H= 1.01

keep in mind that you have to also account for how many atoms of each there are in the molecule. for example, in Ca(OH)2, there are one Ca, two O and two H

so the molar mass of Ca(OH)2= 40.1 + (2 x 16.0) + (2 x 1.01)= 74.12 g/mol

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3 years ago

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nika2105 [10]

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3 years ago

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What is the percent composition by mass of each element in Co(HSO4)2?

MrRissso [65]

Answer:

54.1 % Ca, 43.2 % O, 2.7% H

Explanation:

Molecular formula for calcium hydroxide is Ca(OH)₂

As we don't have a mass of Ca(OH)₂ to find out the percentage composition, we consider that the question refers to 1 mol of compound.

1 mol of hydroxide weighs 74.08 g

1 mol of hydroxide has 1 mol of Ca, therefore 40.08 g are Ca

2 moles of O therefore 32g are O

2 moles of H therefore 2 g are H

Percentage composition is known as (Mass of element/Total mass) . 100

(40.08 / 74.08) . 100 = 54.1 %

(32 / 74.08) . 100 = 43.2 %

(2 / 74.08) . 100 = 2.7%

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2 years ago

Having been heated to 800 K , at some point the tank starts to leak. By the time the leak is repaired, the tank contains only ha

Liula [17]

Answer: The temperature of the gas reduced to 400K.

Explanation:

Stated that ; The pressure remains the same, that is initial and final pressure equals 1atm.

Applying Charles Law

$V1/T1 = V2/T2$

Initial volume V1 = 1

Final volume V2 = 1/2 (halved)

Initial temperature T1 =800K

Final temperature T2 = ?

(1/800) = (1/2)/T2

T2 = 800/2

T= 400K

Therefore, when the volume is halved, the temperature reduced also to half ( 400K)

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3 years ago

Last week you reacted magnesium with a hydrochloric acid aqueous solution and hydrogen gas was produced. Let's say that you coll

miv72 [106K]

Answer:

69.8 kilo Pasacl is the pressure of the hydrogen gas.

Explanation:

$Mg+2HCl\rightarrow MgCl_2+H_2$

Pressure at which hydrogen gas collected = p = 101.2 kilo Pascals

Vapor pressure water = $p^o$ = 31.4 kilo Pascals

The pressure of hydrogen gas = P

The pressure at which gas was collected was sum of vapor pressure of water and hydrogen gas.

$p=P+p^o$

$P =p-p^o=101.2 kPa-31.4 kPa=69.8 kPa$

69.8 kilo Pasacl is the pressure of the hydrogen gas.

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3 years ago