How to determine the mass fraction of sodium carbonate in sodium carbonate and sodium bicarbonate

Go to a certain sample.

After dissolving, excess hydrochloric acid is added to collect the gas produced to calculate the mol amount.

NaHCO3+HCl=NaCl+H2O+CO2 can be calculated according to the equation.

Chemistry throws it so long that I can't remember it

There are several ways to distinguish sodium carbonate from sodium bicarbonate:

1. Heating, sodium bicarbonate has poor thermal stability, and sodium bicarbonate can be decomposed.

2. Take the same amount of dissolved in water, and observe which of the two dissolves more, and the solubility of sodium bicarbonate is small.

3. Take the same amount of dissolved in water, measure its pH value, and the size of sodium carbonate.

4. Add hydrochloric acid dropwise, hydrochloric acid dropwise added to sodium bicarbonate solution, and immediately produce closed air bubbles, and drop added to sodium carbonate solution will not produce bubbles.

5. Add calcium chloride solution, use metathesis reaction, sodium carbonate solution reacts with calcium chloride to produce white precipitate, while sodium bicarbonate will not.

Sodium carbonate is commonly known as pure good alkali, soda, white powder, good thermal stability, and is not easy to decompose when heated.

Sodium bicarbonate, commonly known as baking soda, is a small white crystal, with poor thermal stability and easy to decompose when heated.

The methods for distinguishing sodium carbonate solution from sodium bicarbonate solution include gas method, precipitation method and pH measurement method. You can take an appropriate amount of two solutions to be identified, and after adding a small amount of hydrochloric acid, the sodium bicarbonate solution that can immediately produce bubbles, and the sodium carbonate solution that produces bubbles more slowly.

Gas delay and dry merger method: take an appropriate amount of two solutions to be identified, add a small amount of hydrochloric acid, and immediately produce bubbles of sodium bicarbonate solution. The slower to produce bubbles is the sodium carbonate solution.

Precipitation method: take an appropriate amount of two solutions to be identified, add an appropriate amount of barium chloride solution or calcium chloride solution, and the sodium carbonate solution that can produce precipitation is the sodium carbonate solution.

pH measurement: use pH to measure the dilute solution of the same concentration, and the larger pH is the sodium carbonate solution.

Observation: Both are white in the solid state. Sodium carbonate is observed to be powdery in appearance and sodium bicarbonate in crystalline form.

Heating method: after heating, it is sodium bicarbonate that can produce the gas that makes the clarified lime water turbid, and vice versa; Before and after heating, it is called its mass, and the one whose mass has decreased is sodium bicarbonate, and vice versa.

Here's how:

1. Heating method.

When heated, it is sodium bicarbonate that produces a gas that makes the clarified lime water turbid, and vice versa. Before and after heating, it is called its mass, and the one whose mass has decreased is sodium bicarbonate, and vice versa.

2. Gas method.

Take an appropriate amount of two solutions to be identified, and add a small amount of hydrochloric acid to produce bubbles of sodium bicarbonate solution immediately. The slower to produce bubbles is the sodium carbonate solution.

3. Precipitation method.

Take an appropriate amount of two solutions to be identified, add an appropriate amount of barium chloride solution or calcium chloride solution, and the precipitate can be sodium carbonate solution.

4. pH measurement is a dilute solution of the same concentration measured by pH, and the larger pH is sodium carbonate solution.

Sodium carbonate characteristics

The aqueous solution of sodium carbonate is strongly alkaline (pH = and has a certain degree of corrosiveness, which can metacompose with acids, and can also metabolize with some calcium salts and barium salts. There are three types of sodium carbonate containing crystalline water: Na2CO3·H2O, Na2CO3·7H2O, and Na2CO3·10H2O.

It is more stable, but it can also decompose at high temperatures to produce sodium oxide and carbon dioxide.

Long-term exposure to the air can absorb moisture and carbon dioxide in the air, form sodium bicarbonate, and form hard lumps.

The crystalline hydrate of sodium carbonate (Na2CO3·10H2O) is easily weathered in dry air.

Difference Between Sodium Carbonate and Sodium Bicarbonate:

1. Different common names: Sodium bicarbonate is commonly known as baking soda, also known as raw sodium carbonate or heavy alkali or acid sodium carbonate. Sodium carbonate is also called soda ash, commonly known as soda.

2. Different shapes: sodium bicarbonate It is a white powder. Sodium carbonate is a white powder or fine particle.

3. Different stability: sodium bicarbonate is unstable and easy to decompose when heated, while solid sodium bicarbonate decomposes when heated. Sodium carbonate is heated to 815 °C and melts without decomposition, with strong stability and is not easy to decompose when heated.

4. Different solubility: sodium carbonate is easily soluble in water and exothermic when dissolved. Sodium bicarbonate is slightly less soluble in water than sodium carbonate.

5. The acidity and alkalinity of the aqueous solution are different: the aqueous solution of sodium bicarbonate is slightly alkaline. Sodium carbonate is a strong alkali and weak salt, so its aqueous solution is alkaline.

Take the preparation of 500ml, sodium carbonate solution as an example.

Steps: Step 1: Calculate: mass of sodium carbonate = g required for trace closure.

Step 2: Weighing: Weigh grams of sodium carbonate solids on a balance and pour it into a small beaker.

Step 3: Add an appropriate amount of distilled water to a small beaker containing sodium carbonate solids and stir with a glass rod to dissolve.

Step 4: Pipetting: Inject the solution along the glass rod into a 500 ml volumetric flask.

Step 5: Washing: Wash the beaker 2-3 times with distilled water and pour it into a volumetric flask.

Step 6: Limb splitting volume: pour water to the 1-2cm mark and use a rubber tip dropper to drip to a straight surface with the concave liquid.

Step 7: Shake well: Cover the cork, turn it upside down and shake well.

Step 8: Bottling and labeling.

The relative molecular mass of sodium carbonate is:

The mass fraction of sodium carbonate in sodium hydroxide solids can be chemically calculated. First of all, the molar mass of sodium hydroxide and the molar mass of sodium carbonate need to be known. The molar mass of sodium hydroxide is and the molar mass of sodium carbonate is.

Secondly, the chemical equation of sodium hydroxide and sodium carbonate needs to be known: 2 NaOH + CO2 Na2CO3 + H2O.

Assuming there is a 100g solid of sodium hydroxide, the mass of the sodium hydroxide needs to be converted to moles first. Since the molar mass of sodium hydroxide is, 100g of sodium hydroxide solid contains moles of sodium hydroxide. According to the chemical equation, every 2 moles of sodium hydroxide can produce 1 mole of sodium carbonate, so moles of sodium hydroxide can produce moles of sodium carbonate.

Converting the molar number of sodium carbonate to mass, one can get the mass of sodium carbonate wide hood as. Therefore, in 100g of sodium hydroxide solids, the mass fraction of sodium carbonate is, ie.

In sodium hydroxide solid trembling megabent, if sodium carbonate is present, its mass fraction can be analyzed by the addition of dilute acid to release CO2.

Assuming that the sample contains sodium carbonate of W(G), the addition of excess HCl to completely decompose it will release X(G) of CO2. According to the principle of chemoichiometry, it is obtained:

2naoh + na2co3 → 2na2o + co2 + h2o

Among them, 1 mol of CO2 is derived from 1 mol of Na2CO3, which can be calculated:

n(co2) =x /

n(Na2CO3) = N(CO2) Eggplant 1 = x * 1).

m(na2co3) =n(na2co3) *m(na2co3)

Among them, M(Na2CO3) is the molar mass of sodium carbonate, which is about 106 g mol. Therefore, w(g) m(NaOH) = w(g) m(NaOH) + m(Na2CO3)).

Substituting the above formula, you get.

w(g) /m(naoh) +m(na2co3)) x / * m(na2co3))

Shift the term and simplify the guess, you get:

m(na2co3) =m(na2co3) *x * m(naoh) / * w(g) -x * m(na2co3))

Therefore, the mass fraction of sodium carbonate can be calculated by this formula. It is important to note that the sample reacts completely with the acid during the experiment, and the necessary purification and calibration are carried out to ensure that the experimental results are correct and reliable.

Sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) can react in water to form sodium bicarbonate (NaHCO3) and sodium hydroxide, and the chemical equation of the reaction is as follows:

naoh + na2co3 → 2nahco3

Therefore, for the sodium carbonate fraction in sodium hydroxide solids, the mass fraction of sodium bicarbonate in the reaction product can be determined by experimental methods, and then the initial mass of sodium carbonate can be calculated according to the chemical equation and the molar ratio relationship of the reactants.

The specific experimental method can be: take a certain amount of sodium hydroxide solid, add a certain amount of water to dissolve, and then slowly add a certain amount of sodium carbonate solution dropwise to make it all react to produce sodium bicarbonate. Then, the mass fraction of the initial sodium bicarbonate can be calculated by filtering, drying, weighing and other methods to separate and measure the mass fraction of sodium bicarbonate.

It should be noted that the reaction conditions need to be strictly controlled in the experiment to avoid other side reactions or incomplete reactions leading to errors in the experimental results.

In sodium hydroxide solids, sodium carbonate is an impurity. Its mass fraction refers to the ratio of the mass of sodium carbonate to the total mass in a given amount of sodium hydroxide. Since both the chemical formulas of sodium hydroxide and sodium carbonate contain sodium deficiency scripts, the presence of sodium carbonate in sodium hydroxide solids affects the amount of sodium in them.

Specifically, the presence of sodium carbonate will reduce the sodium content of sodium hydroxide. Therefore, if you want to calculate the mass fraction of sodium carbonate in sodium hydroxide solids, you need to first determine the content of sodium in it, then subtract the mass of sodium from the total mass to obtain the mass of sodium carbonate, and finally use the ratio of sodium carbonate mass to total mass. The specific value needs to be determined according to the actual situation.

There is no sodium carbonate in sodium hydroxide solids. The chemical formula of sodium hydroxide is NaOH and is an ionic compound consisting of sodium ions and hydroxyl ions and has no carbonate ions. Sodium carbonate has the chemical formula Na2CO3 and is an ionic compound consisting of sodium ions, carbonate off-mask fronts, and oxygen ions.

Although both sodium hydroxide and sodium carbonate contain "sodium" in their chemical names, their chemical composition and chemical properties are different. In the sodium hydroxide solid, there is only sodium hydroxide, a compound, and no other impurity compounds, so there is no sodium carbonate.