The clouds are grey and ground is wet. A quantitative B qualitative

How many grams of lead sulfide from when 10.0 g of lead are heated with 3.0 g of sulfur

zaharov [31]

The reaction forms 11.5 g PbS.

We have the masses of two reactants, so this is a limiting reactant problem.

We know that we will need a balanced equation with masses, moles, and molar masses of the compounds involved.

Step 1. Gather all the information in one place with molar masses above the formulas and everything else below them.

M_r: 207.2 32.06 239.28

Pb + S → PbS

Mass/g: 10.0 3.0

Step 2. Calculate the moles of each reactant

Moles of Pb = 10.0 g Pb × (1 mol Pb /207.2 g Pb) = 0.048 26 mol Pb

Moles of S = 30 g S × (1 mol S/32.06 g S) = 0.9357 mol S

Step 3. Identify the limiting reactant

Calculate the moles of PbS we can obtain from each reactant.

From Pb: Moles of PbS = 0.048 26 mol Pb × (1 mol PbS/1 mol Pb )

= 0.048 26 mol PbS

From S: Moles of S = 0.9357 mol S × (1 mol PbS/1 mol S) = 0.9357 mol PbS

Pb is the limiting reactant because it gives the smaller amount of PbS.

Step 4. Calculate the mass of PbS.

Mass = 0.048 26 mol PbS × (239.28 g PbS/1 mol PbS) = 11.5 g PbS

The reaction produces 11.5 g PbS.

4 0

4 years ago

What bond vibrations and stretching frequencies should you observe in the IR spectrum of caffeine?

Margarita [4]

The bond vibrations that can be observed in the IR spectrum of caffeine :

i) asymmetric, ii) symmetric, iii) wagging, iv) twisting, v) scissoring, vi) rocking

while the observable stretching frequencies are ; 1700, 1300, 2900, 1500 and 3000.

Caffeine is a polyatomic molecule ( contains more than two atoms bonded via covalent bonds ) therefore its atoms can vibrate in three dimensions ( x, y, z ).therefore the bond vibrations that can be observed in the IR spectrum of caffeine are : asymmetric, symmetric, wagging, twisting, scissoring, and rocking.

The observable stretching frequencies that are in the IR spectrum of caffeine ; C = O is 1700 , C - H is 1300, C -H is 2900, C -N is 1500, and N -H = 3000.

Hence we can conclude The bond vibrations that can be observed in the IR spectrum of caffeine : i) asymmetric, ii) symmetric, iii) wagging, iv) twisting, v) scissoring, vi) rocking and the observable stretching frequencies are ; 1700, 1300, 2900, 1500 and 3000.

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