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4 years ago

Calculate the number of moles of caco3 (calcium carbonate, or limestone) in a 20.0g sample of this substance

1 answer:

6 0

First calculate for the molar mass of the given formula unit, CaCO₃. This can be done by adding up the product when the number of atom is multiplied to its individual molar mass as shown below.

molar mass of CaCO₃ = (1 mol Ca)(40 g Ca/mol Ca) + (1 mol C)(12 g of C/1 mol of C) + (3 mols of O)(16 g O/1 mol O) = 100 g/mol of CaCO₃

Then, divide the given amount of substance by the calculated molar mass.
number of moles = (20 g)(1 mol of CaCO₃/100 g)
number of moles = 0.2 moles of CaCO₃

Answer: 0.2 moles

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Would your results be he same if 1.5 g of barium chloride was used instead of 1.3 g? same with 0.7 g of barium chloride?

pickupchik [31]

For a chemical reaction, the results would be the same with different amounts of barium chloride present if barium chloride is not the limiting reactant of the reaction. The limiting reactant is the substance that is totally consumed when the reaction proceeds to completion. In other words, it dictates the amount of products that will be produced. Otherwise, if barium chloride is the limiting reactant, the amount of barium chloride present would definitely affect the results.

6 0

3 years ago

The freezing point of ethanol, CH3CH2OH, is -117.300 °C at 1 atmosphere. Kf(ethanol) = 1.99 °C/m

MAXImum [283]

Answer : The molecular weight of this compound is 891.10 g/mol

Explanation : Given,

Mass of compound = 12.70 g

Mass of ethanol = 216.5 g

Formula used :

$\Delta T_f=i\times K_f\times m\\\\T_f^o-T_f=i\times T_f\times\frac{\text{Mass of compound}\times 1000}{\text{Molar mass of compound}\times \text{Mass of ethanol}}$

where,

$\Delta T_f$ = change in freezing point

$T_f^o$ = temperature of pure ethanol = $-117.300^oC$

$T_f$ = temperature of solution = $-117.431^oC$

$K_f$ = freezing point constant of ethanol = $1.99^oC/m$

i = van't hoff factor = 1 (for non-electrolyte)

m = molality

Now put all the given values in this formula, we get

$(-117.300)-(-117.431)=1\times 1.99^oC/m\times \frac{12.70g\times 1000}{\text{Molar mass of compound}\times 216.5g}$

$\text{Molar mass of compound}=891.10g/mol$

Therefore, the molecular weight of this compound is 891.10 g/mol

7 0

3 years ago

**Narrowed it down please help!**

natka813 [3]

Answers:

1. B.)

2. Both A.) and B.)

3. A.)

Step-by-step explanation:

1. Ions in gas phase

A plasma is a gas consisting of electrons and positively charged ions.

Because the particles are ions and electrons, rather than neutral atoms or molecules as in ordinary gases, scientists consider a plasma to be a fourth state of matter.

2. Kinetic Molecular Theory

Both activities illustrate the postulate.

A.) If the particles are extremely small and far apart, most of the volume of a gas is empty space. That's why it's easy to push the plunger of a capped nozzle syringe containing a gas.

B.) If the particles are far apart, it's easy for a coloured gas to spread into an inverted jar placed on top of a jar containing the gas.

3. Hot air balloon

The high temperature in the balloon makes the gas molecules spread apart according to Charles's law, because this law describes how a gas will behave at constant pressure.

As the hot air escapes from the vent, the combined mass of balloon + hot air becomes less than the mass of cold air that it displaces, and the balloon rises.

B.) is wrong. Boyle's law applies only when both the number of moles and the temperature remain constant.

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3 years ago

each of the two days of the year when the noon sun is furthest north or south of the equator is called a

Luba_88 [7]

Its called a Solstice :)

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3 years ago

Which diagram is correct

elixir [45]

Answer:

The answer to the question is option D

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2 years ago