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2 years ago

Which tool is used to measure mass?

Chemistry

2 answers:

Ostrovityanka [42]2 years ago

7 0

Answer: A balance is the tool used to determine an object's mass

Explanation:

slega [8]2 years ago

3 0

Answer:

kilogram is used to measure to mass

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Calculate the molarity of a solution prepared by dissolving 1.495 moles of lioh in enough water to give a final volume of 750. m

zhenek [66]

Molarity can be defined as the number of moles of substance dissolved in 1 L of solution.
In the given question ,
number of LiOH moles - 1.495 mol
Dissolved volume - 750 mL
molarity is calculated for 1 L = 1000 mL
In 750 mL - 1.495 mol of LiOH is dissolved
Therefore in 1000 mL - 1.495 mol / 750 mL x 1000 = 1.99 mol

4 0

2 years ago

Solid sodium hydrogen carbonate, NaHCO3, decomposes on heating according to the equation:

tekilochka [14]

Answer:

See explanation

Explanation:

First, let's write the balanced equation again:

2 NaHCO3(s) <-> Na2CO3(s) + H2O(g) + CO2(g)

Now, we know that the total pressure was 7.76 atm. This total pressure, is the sum of the pressure of water and CO2 like this:

Ptotal = Pwat + PCO2 (1)

This is the dalton's law for partial pressures.

The pressure can be also be relationed with the moles

Ratio of mole = Ratio of pressure

so, taking this in consideration we can say the following:

Pwater/PCO2 = moles water / moles CO2

As the only components exerting pressure are CO2 and Water (Because they are in gas phase), the total pressure can be splitted between the two of them so:

Pwater = Ptotal/2

Pwater = 7.76 / 2 = 3.88 atm

With this pressure, and using the ideal gas equation, we can know the moles of water:

PV = nRT

n = PV/RT using R = 0.082 L atm / K mol

n = 3.88 * 5 / 0.082 * (160+273)

n = 0.546 moles of water

b) now that we have the moles of water, we can actually know the moles that reacted originally from the sodium carbonate by stechiometry.

2NaHCO3(s) <-> Na2CO3(s) + H2O(g) + CO2(g) MMCO2 = 84 g/mol

the moles of NaHCO3 initially:

n = 100 / 84

n = 1.19 moles

so, If 1.19 moles of NaHCO3 reacted, and only produces 0.546 moles of water and CO2, then, the remaining moles of NaHCO3 is:

remaining moles = 1.19 - 0.546 = 0.644 moles

therefore the mass remaining:

mCO2 = 0.644 * 84

mCO2 = 54.096 g

c) As it was stated before, only the gaseous components are involved in the pressure, thus, in the kp expression which is:

Kp = Pwater * PCO2

Kp = 3.88 * 3.88

Kp = 15.0544

d) As the total pressure is 7.76 atm and the fact that NaHCO3 is solid, this component is not exerting any pressure in the reaction, as seen in the Kp expression, so it won't matter that if we raise a little the quantity of the reactant, it still has some remaining.

3 0

3 years ago

What are the four points of Dalton's Theory?<br>

WARRIOR [948]

1. Elements are composed of atoms that are indestructible

2. All atoms of a given element are identical; same size/mass/chemical properties

3. Atoms of 1 element are different from the atoms of other elements

4. Compounds are composed of atoms with more than 1 element. The relative number of atoms for each element are of a given compound are always going to be the same.

(Extra one) 5. Chemical reactions are only ever going involve the rearrangement of the atoms. Atoms are not created/destroyed during the chemical reactions. (Law of Conservation of Mass: nothing can ever be created or destroyed.)

3 0

2 years ago

What is the correct equilibrium constant expression for the following heterogeneous equilibrium? 4HCl (g) + O2 (g) ⇄ 2H2O (l) +

gizmo_the_mogwai [7]

Answer:

$Kc=[Cl2]2/[HCl]4[O2]$

Explanation:

Hello,

In this case, the law of mass action, allows us to study the mathematical expression regarding an equilibrium chemical reaction allowing us to see a relationship between the equilibrium constant and the concentration of both the products and reactants at equilibrium for either gaseous or aqueous substances only. Such relationship is assembled as the quotient between the concentration of products at equilibrium over the concentration of reactants at equilibrium equaling the equilibrium constant. Thus, for the given chemical reaction, such expression will have the concentration of chlorine at the numerator and both the concentrations of hydrogen chloride and oxygen at the denominator since water is liquid so it is not included in the shown below equation:

$Kc=\frac{[Cl]^2}{[HCl]^4[O_2]}$

Therefore the answer is: Kc=[Cl2]2/[HCl]4[O2].

Best regards.

5 0

3 years ago

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Find the mass of 1 mole of CuS

andrezito [222]

95.611 g/mol that's the answers

4 0

2 years ago