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4 years ago

Scientific law

Chemistry

2 answers:

VARVARA [1.3K]4 years ago

8 0

More detail? If you can send it.

Lorico [155]4 years ago

5 0

A scientific law are statements, based on repeated experiments or observations.

A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method. (I’ll come back with more answers)

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The reaction of Cr2O3 with silicon metal at high temperatures will make chromium metal. 2CrO3(s) + 3Si(s)----> 4Cr(l) + 3SiO2

nalin [4]

Answer: 51.45 grams of excess reagent is left after the completion of reaction.

Explanation: For the calculation of moles, we use the formula:

$Moles=\frac{\text{Given mass}}{\text{Molar mass}}$ ....(1)

For Si

Given mass = 92 grams

Molar mass = 28g/mol

Putting values in equation 1, we get:

$Moles=\frac{92g}{28g/mol}=3.285moles$

For $Cr_2O_3$

Given mass = 112 grams

Molar mass = 116g/mol

Putting values in equation 1, we get:

$Moles=\frac{112g}{116g/mol}=0.965moles$

The reaction follows:

$2Cr_2O_3(s)+3Si(s)\rightarrow 4Cr(l)+3SiO_2(s)$

By Stoichiometry,

2 moles of $Cr_2O_3$ reacts with 3 moles of silicon

So, 0.965 moles of $Cr_2O_3$ reacts with = $\frac{3}{2}\times 0.965$ = 1.4475 moles of Silicon.

As, the moles of silicon is more than the required amount and is present in excess.

So, the excess reagent for the reaction is Silicon.

Moles of silicon remained after reaction = 3.285 - 1.4475 = 1.8375 moles

To calculate the amount of Silicon left in excess is calculated by using equation 1:

$1.8375=\frac{\text{Given mass}}{28}$

Amount of Silicon in excess will be 51.45 grams.

5 0

4 years ago

The form of oxygen that combines three oxygen atoms to each molecule, is found in the stratosphere and shields out harmful UV ra

Dmitry_Shevchenko [17]

This form of the oxygen molecule is Ozone, O3.

7 0

3 years ago

Acetaminophen (C8H9NO2) is the active ingredient in many nonprescription pain relievers. Each tablet contains 500 mg of acetamin

ohaa [14]

1) Molar mass C8H9NO2

Element Atomic mass    # of atoms mass
   g/mol g
C 12 8 12*8 = 96
H 1 9    1*9 = 9
N    14    1    14*1 = 14
O    16 2 16*2 = 32

      molar mass = 96 + 9 + 14 + 32 = 151 g/mol

2) Number of mols in a tablet

# of moles = mass / molar mass = 0.500 g / 151 g/mol = 0.003311 moles

3) 3 doses * 2 tablets * 0.003311 moles / tablet = 0.020 moles

7 0

3 years ago

During an experiment, 104 grams of calcium carbonate reacted with an excess amount of hydrochloric acid. If the percent yield of

postnew [5]

Answer:

92.4 grams.

Explanation:

From the balanced reaction:

CaCO₃ + 2HCl → CaCl₂ + CO₂ + H₂O,

1.0 mole of CaCO₃ reacts with 2.0 moles of HCl to produce 1.0 mole of CaCl₂, 1.0 mole of CO₂, and 1.0 mole of H₂O.

We need to calculate the no. of moles of (104 g) of CaCO₃:

no. of moles of CaCO₃ = mass/molar mass = (104 g)/(100.08 g/mol) = 1.039 mol.

Using cross multiplication:

1.0 mole of CaCO₃ produce → 1.0 mole of CaCl₂.

∴ 1.039 mole of CaCO₃ produce → 1.039 mole of CaCl₂.

∴ The amount of CaCl₂ produced = no. of moles x molar mass = (1.039 mol)(110.98 g/mol) = 114.3 g.

∵ percent yield of the reaction = [(actual yield)/(theoretical yield)] x 100.

Percent yield of the reaction = 80.15%, theoretical yield = 115.3 g.

∴ actual yield = [(percent yield of the reaction)(theoretical yield)]/100 = [(80.15%)/(115.3 g)] / 100 = 92.42 g ≅ 92.4 g.

7 0

3 years ago

How many mols are in 151 g of dinitrogen monoxide?

oksano4ka [1.4K]

Answer:

3.43 moles

Explanation:

To convert moles into grams you must take the number of grams and divide it by the atomic mass of the compound.

in this case, grams is 151 and N2O has an atomic mass of 44.013

so your equation would look like

151/44.013=3.430804535

your answer would be 3.43 moles

8 0

3 years ago