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3 years ago

How many grams of aluminum chloride are needed to react completely with 1.084g lithium sulfide?

1 answer:

5 0

Molar mass :

Li₂S = 45.947 g/mol

AlCl₃ = 133.34 g/mol

3 Li₂S + 2 AlCl₃ = 6 LiCl + Al₂S₃

3 * 45.947 g Li₂S ----------> 2 * 133.34 g AlCl₃
1.084 g Li₂S ----------------> ?

Mass Li₂S = 1.084 * 2 * 133.34 / 3 * 45.947

Mass Li₂S = 289.08112 / 137.841

Mass Li₂S = 2.0972 g

hope this helps!

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Ms. Crawford gave the following instructions to her science class: • Place an empty water bottle on the table and remove the lid

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3 years ago

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Which element would you expect to be more metallic? (a) Ca or Rb (b) Mg or Ra (c) Br or I

svlad2 [7]

Explanation:

When we move across a period from left to right then there will occur an increase in electronegativity and also there will occur an increase in non-metallic character of the elements.

As calcium (Ca) is a group 2A element and rubidium (Rb) is a group 1A element. Hence, Rb being an alkali metal is more metallic in nature than calcium (alkaline earth metal).

Both magnesium (Mg) and radium (Ra) are group 2A elements. And, when we move down a group then as the size of element increases so, it becomes easy of the metal atom to lose an electron.

As a result, there occurs an increase in metallic character of the element. Hence, Radium (Ra) is more metallic in nature than magnesium (Mg).

Also, both bromine and iodine are group 17 elements. Since, both of them are non-metals and non-metallic character increases on moving down the group.

Therefore, bromine (Br) is more metallic than iodine.

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3 years ago

Which represents the self ionization of water at 25 degrees

gayaneshka [121]

This question comes with four answer choices:

A. H2O + H2O ⇄ 2H2 + O2

B. H2O + H2O⇄ H2O2 + H2

C. H2O + H2O ⇄ 4H+ + 2O2-

D. H2O + H2O ⇄ H3O+ + OH-

Answer: option D. H2O + H2O ⇄ H3O+ + OH-

(the +sign next to H3O is a superscript, as well as the - sing next to OH)

Explanation:

The self-ionization of water, or autodissociation, produces the two ions H3O(+) and OH(-). The presence of ions is what explain the electrical conductivity of pure water.

In this, one molecule of H2O loses a proton (H+) (deprotonates) to become a hydroxide ion, OH−. Then, he hydrogen ion, H+, immediately protonates another water molecule to form hydronium, H3O+.

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3 years ago

Calculate the hydronium ion and hydroxide ion concentrations in human blood at 25oc

sukhopar [10]

Using the equation, pH = − log [H+] , we can solve for [H+] as,

− pH = log [H+] ,

[H+] = 10−pH.

Exponentiate both sides with base 10 to "undo" the common logarithm. The hydrogen ion concentration of blood with pH 7.4 is,

[H+] = 10−7.4 ≈ 0.0000040 = 4.0 × 10−8 M.

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3 years ago

Which of the following statements regarding alpha particles are true? Check all that apply.a. Alpha particles have a mass number

egoroff_w [7]

Answer:

The only true statement is:

a. Alpha particles have a mass number of 4

Explanation:

Alpha particles are radiactive particles equivalent to a helium nucleus, so they have two protons and two neutrons.

Hence, alpha particles, α, are represented as:

⁴₂He

The superscript 4 to the left of the chemical symbol is the mass number: 2 protons + 2 neutrons = 4

The subscript 2 to the left of the chemical symbol is the atomic number: 2 protons = 2.

Hence, the statement "a. Alpha particles have a mass number of 4" is true.

As for the other statements, you have:

b. Alpha particles have a nulear charge of +1: false

Since, these particles are the nucleous of the helium atom, the nuclear charge equals the number of protons of this atom: +2. Hence, the statement is false.

c. Alpha particle formation is accompanied by the conversion of a proton into a neutron and d. Alpha particle formation is accompanied by the conversion of a neutron into a proton. (both false)

The conversion of a protons into a neutrons and the conversion of a neutron into a proton are product of other kind of radiactive desintegrations.

The conversion of a proton into a neutron involves the emission of a positron ( particle with same mass as the electron but positive charge) from the nucleus, which is represented as ⁰₊₁β.

The conversion of a neutron into a proton involves the emssion of an electron from the nucleus, which is the emission of a beta particle represented as ⁰₋₁β.

Therefore, these last two statements are also false.

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3 years ago