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lys-0071 [83]
3 years ago
7

How many moles are there in 34.8 grams of Calcium?

Chemistry
1 answer:
olga55 [171]3 years ago
5 0

Answer:

Number of moles = 0.87 mol

Explanation:

Given data:

Mass of calcium = 34.8 g

Number of moles = ?

Solution:

Formula:

Number of moles = mass/molar mass

Molar mass of calcium = 40 g/mol

By putting values,

Number of moles = 34.8 g/ 40 g/mol

Number of moles = 0.87 mol

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Use the rules (in order) to assign oxidation numbers to each of the elements in the compounds below.
xz_007 [3.2K]

Answer:

Explanation:

The oxidation number is an integer that represents the number of electrons that an atom receives or makes available to others when it forms a given compound.

The oxidation number is positive if the atom loses electrons, or shares them with an atom that has a tendency to accept them. And it will be negative when the atom gains electrons, or shares them with an atom that has a tendency to give them up.

Chemical compounds are electrically neutral. That is, the charge that all the atoms of a compound contribute must be globally null. That is, when having positive or negative charges in a compound, their sum must be zero.

There are some rules for determining oxidation numbers in compounds. Among them it is possible to mention:

  • Hydrogen (H) has an oxidation number +1 with nonmetals and - 1 with metals.
  • Oxygen (O) presents the oxidation number -2
  • Fluorine F has a unique oxidation state -1

Then:

  • NOF: N+(-2)+(-1)=0 → N=3 → oxidation number of  nitrogen (N) is +3, oxidation number of oxygen (O) is -2 and oxidation number of  fluorine (F) is -1.
  • ClF₅: Cl + 5*(-1)=0 → Cl= 5 → oxidation number of  chlorine (Cl) is +5 and oxidation number of  fluorine (F) is -1.
  • H₂SO₃: 2*(+1)+S+3*(-2)=0 → S=4 → oxidation number of hydrogen (H) is +1, oxidation number of oxygen (O) is -2 and oxidation number of sulfur (S) is +4.
8 0
3 years ago
The solubility of kcl in ethanol is 0.25 g / 100 ml at 25 oc. how does this compare to the solubility of kcl in water?
Furkat [3]
Solubility data of a certain solute with a certain solvent is empirical. There are constant values for this at varying temperatures. For KCl in water at 25°C, the solubility is 35.7 g/100 mL of water. When you compare this with the solubility data of KCl with ethanol, this means that KCl is more soluble in water than in ethanol. This is true because KCl is an ionic salt which is very soluble in water.
8 0
3 years ago
These are elements that
agasfer [191]

Answer:

metals are those element that have luster,malleable, ductile good conductors of heat and électricity, must have high melting and boiling points, and lose electrons in chemical reactions.

6 0
2 years ago
4. How would you calculate the poH of a base when given the<br><br> concentration of [OH]-?
Novay_Z [31]

Answer:

Use pOH = -log₁₀ [OH-]

Explanation:

pOH can be calculated from the concentration of hydroxide ions using the formular below:

pOH = -log₁₀ [OH-]

The pOH is the negative logarithm of the hydroxide ion concentration.

3 0
2 years ago
A measured sample of argon gas has a volume of 20.0 L at a pressure of 660 mm Hg. What is the final volume
valkas [14]

Answer:

C . 24 L

Explanation:

Given data:

Initial volume of gas = 20.0 L

Initial pressure of gas = 660 mmHg

Final volume = ?

Final pressure = 550 mmHg

Solution:

The given problem will be solved through the Boly's law,

"The volume of given amount of gas is inversely proportional to its pressure by keeping the temperature and number of moles constant"

Mathematical expression:

P₁V₁ = P₂V₂

P₁ = Initial pressure

V₁ = initial volume

P₂ = final pressure

V₂ = final volume  

Now we will put the values in formula,

P₁V₁ = P₂V₂

660 mmHg × 20.0 L = 550 mmHg × V₂

V₂ = 13200 mmHg. L/ 550 mmHg

V₂ = 24 L

3 0
3 years ago
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