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2 years ago

Can anyone teach me what is criss cross method in chemistry

Chemistry

1 answer:

Solnce55 [7]2 years ago

8 0

Answer:

In the criss-cross method, the numerical value of the ion charge of the two atoms are crossed over, which becomes the subscript of the other ion. Using this technique, we will write the chemical formula of the given compounds.

Criss cross the absolute values to give Al2O3. To find the formula for magnesium oxide:- The oxidation number of Mg is +2 and oxygen is -2. Criss cross the absolute values to give Mg2O2In this example there is a common factor of 2 so divide by 2 to give MgO.

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Aspirin (C9H8O4) is synthesized by reacting salicylic acid (C7H6O3) with acetic anhydride (C4H6O3). The balanced equation isC7H6

prisoha [69]

Answer:

For a: The mass of acetic anhydride needed is 73.91 grams.

For b: The theoretical yield of aspirin is 130.43 grams.

Explanation:

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$ .....(1)

For a:

Given mass of salicylic acid = $1.00\times 10^2g=100g$

Molar mass of salicylic acid = 138.121 g/mol

Putting values in equation 1, we get:

$\text{Moles of salicylic acid}=\frac{100g}{138.121g/mol}=0.724mol$

For the given chemical reaction:

$C_7H_6O_3+C_4H_6O_3\rightarrow C_9H_8O_4+CH_3COOH$

By stoichiometry of the reaction:

1 mole of salicylic acid reacts with 1 mole of acetic anhydride.

So, 0.724 moles of salicylic acid will react with = $\frac{1}{1}\times 0.724=0.724mol$ of acetic anhydride.

Now, to calculate the mass of acetic anhydride, we use equation 1:

Moles of acetic anhydride = 0.724 moles

Molar mass of acetic anhydride = 102.09 g/mol

Putting values in equation 1, we get:

$0.724mol=\frac{\text{Mass of acetic anhydride}}{102.09g/mol}\\\\\text{Mass of acetic anhydride}=73.91g$

Hence, the mass of acetic anhydride needed is 73.91 grams.

For b:

By stoichiometry of the reaction:

1 mole of salicylic acid is producing 1 mole of aspirin.

So, 0.724 moles of salicylic acid will produce = $\frac{1}{1}\times 0.724=0.724mol$ of aspirin.

Now, to calculate the mass of aspirin, we use equation 1:

Moles of aspirin = 0.724 moles

Molar mass of aspirin = 180.158 g/mol

Putting values in equation 1, we get:

$0.724mol=\frac{\text{Mass of aspirin}}{180.158g/mol}\\\\\text{Mass of aspirin}=130.43g$

Hence, the theoretical yield of aspirin is 130.43 grams.

4 0

3 years ago

2n2+5O2 = 2N2O5 what mass of nitrogen is required to react with 16 grams of oxygen

bezimeni [28]

Answer:

Explanation:

5.6

5 0

3 years ago

In the Lewis structure of AB4 where B is more electronegative than A. Both are main group elements where A has 8 valence electro

Ivenika [448]

Answer:

1. 36

2. Two

Explanation:

The Lewis structure shows the valence electrons present in a compound. Usually the valence electrons are shown as dot structures around the symbol of the elements involved in the compound.

For a compound AB4 where B is more electronegative than A and A has 8 electrons in its valence shell, there will be thirty six valence electrons on the outermost shell of the molecule.

There are six electron pair domains present in the molecule, four bond pairs and two lone pairs. The molecule is in a square planar geometry.

5 0

4 years ago

When 3.2g of ammonium chloride is dissolved in 75g of water, the temperature of the solution decreases from 22.8 C to 20.1 C. Wh

ser-zykov [4K]

Dissolving NH4Cl in H2O is an endothermic solution process. You measure how much it cools the solution by the temperature of the H2O.
q = mass H2O x specific heat H2O x (Tfinal-Tinitial) 
The q you measure is for 3.2g/53.4g or q/0.0599 mol. You want to convert that to q/1 mol.

7 0

4 years ago

Read 2 more answers

13. Which ONE of the following is a chemical process? A. The liquid propane in a gas grill burns in a flame. B. Salt (sodium chl

Shkiper50 [21]

Answer:

A. The liquid propane in a gas grill burns in a flame.

Explanation:

Chemical changes is the change which occur when the substance combines with the another to form a completely new substance.

Considering Options B, C and D, the identity of each specie is not changed but the state is changed and thus, these are physical changes.

On the other hand, Option A, when propane is being burnt in the flame , it changes to gas and its identity is lost. Thus, is a chemical change.

4 0

3 years ago

Can anyone teach me what is criss cross method in chemistry​

Can anyone teach me what is criss cross method in chemistry