Water double displacement reactions

Ammonium perchlorate is a colorless, crystalline compound having a density of 1.95 g/mL and a molecular weight of 117.5. It is prepared by a double displacement reaction between sodium perchlorate and ammonium chloride, and is crystallized from water as the anhydrous salt. 

Remember that an acid-base reaction is a double displacement reaction. Therefore, if sulfuric acid and potassium hydroxide are mixed, the positive ions trade places. The hydrogen ions from the sulfuric acid will react with the negative hydroxide ions to form water. Because a hydrogen ion has a charge of + 1 and a hydroxide ion has a charge of -1, they bond in a 1 1 ratio ... 

Because this is a reaction between an acid and a base, it will be a double displacement reaction, and the positive ions will switch places. The potassium ion will react with the sulfate ion, forming the salt potassium sulfate (K2S04). And the hydrogen ion in the acid will react with the hydroxide ion in the base to form HOH, or water (H20). 

Most phosphodiesterases catalyze transfer of the phosphoryl group to water with retention of configuration. Again, in keeping with other evidence for phosphorylenzyme intermediates, these probably represent double displacement reactions. One exception occurs with the 3 — 5 exonuclease of T4 DNA polymerase (Chapter 14) its reactions proceed with inversion.49... 

Many double displacement reactions occur between ionic compounds that are dissolved in water. Sometimes one of the products of a double displacement reaction will come out of solution, usually as a gas or a precipitate. Solutions are mixtures of two or more substances, called the solutes, dissolved in another substance, the solvent. For example, salt water is a solution. The salt is the solute and the water is the solvent. In a solution, it is impossible to see the separate parts. But if two chemicals that are dissolved in water... 

In the double displacement reaction above, dissolved sodium cyanide (NaCN) and sulfuric acid (H2S04) react to form sodium sulfate (Na2S04) and an extremely poisonous gas called hydrogen cyanide (HCN). The (aq) means these substances are an aqueous solution. An aqueous solution is made by dissolving chemicals in water. In this reaction, the sodium cyanide, sulfuric acid, and sodium sulfate are all dissolved in water. The (g) that follows the formula for hydrogen cyanide indicates that this chemical is a gas. The hydrogen cyanide will bubble out of the solution, leaving behind the sodium sulfate that is still dissolved in the water. 

Acid-base reactions are a special type of double displacement reaction. Acid-base reactions occur when an acid and a base react with one another. An acid is a compound that contains hydrogen and gives off hydrogen ions (H+) when it is dissolved in water. Bases, on the other hand, produce hydroxide ions (OH ) when they are dissolved in water. 

Calcium oxide and water yield calcium hydroxide a composition reaction. Calcium chloride and sodium carbonate yield calcium carbonate and sodium chloride a double displacement reaction. 

Acid-base reactions (neutralization). An acid, which contributes H+ (H30+) ions, and a base, which contributes OH- ions, undergo metathesis to produce water (HOH or H2O) and a salt. Isn t this a special case of a double displacement reaction ... 

A double displacement reaction involves the exchange of cations between two ionic compounds, usually in aqueous (water) solution. A double displacement reaction is also known as a double replacement reaction. 

How do you know that the precipitate is BaS04 and not KC1 More generally, how can you predict whether a precipitate will be formed in a double displacement reaction In this chapter, you will be given information on solubility as you need it. You will learn more about how to predict whether a compound is soluble or not in Chapter 9. Barium sulfate, BaS04 is not soluble in water, while potassium chloride, KC1, is. Therefore, a reaction will take place and barium sulfate will be the precipitate. 

What happens if both products are soluble ionic compounds Both ionic compounds will be ions dissolved in the water. If neither product precipitates out, no reaction occurs. Try the following problem to practise writing the products of double displacement reactions and predicting their states. 

The reaction of hydrochloric acid and sodium carbonate, Na2C03 (washing soda), is a double displacement reaction. This reaction initially forms sodium chloride and carbonic acid, H2CO3. The carbonic acid spontaneously decomposes to water and carbon dioxide gas. 

In certain cases, you know that a double displacement reaction has occurred because a gas is produced. The gas is formed when one of the products of the double displacement reaction decomposes to give water and a gas. 

Another double displacement reaction results in the formation of gaseous ammonia, NH3. Ammonia, a pungent-smelling gas, is an important industrial chemical. It is used as a fertilizer and, when dissolved in water, as a household cleaner. Ammonium hydroxide is formed in the reaction below... 

Neutralization reactions are a special type of double displacement reaction that produces water. Neutralization involves the reaction of an acid with a base to form water and an ionic compound. You will learn more about neutralization reactions in Chapter 10. For example, the neutralization of hydrogen nitrate (nitric acid) with sodium hydroxide (a base) is a double displacement reaction. 

Most often, double displacement reactions result in the formation of a precipitate. However, some double displacement reactions result in the formation of an unstable compound which then decomposes to water and a gas. 

The reaction of an acid and a base—a neutralization reaction—is also a type of double displacement reaction. It results in the formation of a salt and water. 

For each reaction in Table B, write the appropriate balanced chemical equation for the double displacement reaction. Then write a balanced chemical equation for the decomposition reaction that leads to the formation of a gas and water. 

Double Displacement Reactions That Produce Water... 

The neutralization reaction between an acid and a base is a very important double displacement reaction. In a neutralization reaction, water results when an H+ ion from the acid bonds with an OH ion from the base. 

Suppose that you have a sample of water. You want to know what, if any, ions are dissolved in it. Today technological devices, such as the mass spectrometer, make this investigative work fairly simple. Before such devices, however, chemists relied on wet chemical techniques experimental tests, such as submitting a sample to a series of double displacement reactions. Chemists still use wet chemical techniques. 

Figure 13 shows the result of the reaction between KI and Pb(N03)2- The products are a yellow precipitate of Pbl2 and a colorless solution of KNO3. From the equation, it appears as though the parts of the compounds just change places. Early chemists called this a double-displacement reaction. It occurs when two compounds in aqueous solution appear to exchange ions and form two new compounds. For this to happen, one of the products must be a solid precipitate, a gas, or a molecular compound, such as water. Water is often written as HOH in these equations. 

Suppose a drinking-water supply contains Ba ". Using solubility rules, write a net ionic equation for a double-displacement reaction that indicates how Ba " might be removed. 

In a double-displacement reaction, the ions of two compounds switch places such that two new compounds form. One of the products must be a solid, a gas, or a molecular compound, such as water, for a reaction to occur. 

Double replacement reactions can be misleading, as they are written, because the compounds that are written as products do not always form. You should pay attention to subscripts to see the form of the products. If the phase is solid, liquid, or gas, then the product will actually form, at least to some extent. If the subscript is aq (for aqueous ), it means that the ions are dissociated in water. Double replacement reactions are also called double displacement reactions. 

In double-displacement reactions, the positive portions of two ionic compounds are interchanged. For a double-displacement reaction to take place, at least one of the products must be a precipitate or water. An example of a double-displacement reaction is shown in Figure 6.11. 

When clear aqueous solutions of lead(II) nitrate and potassium iodide are mixed, a double-displacement reaction takes place and a yellow solid appears in the mixture. This solid is lead(II) iodide, and it precipitates out because it is insoluble in water, unlike the two reactants and the other product. 

When a solution of 25.0 g of silver nitrate in 100 g of water is mixed with a solution of 10.0 g of magnesium chloride in 100 g of water, a double displacement reaction occurs. The balanced chemical equation is shown below. Which is the limiting reactant ... 

Sometimes a double-displacement reaction has one produa that is insoluble in water. As that produa forms, it emerges, or precipitates, from the solution as a solid. This process is called precipitation, such a reaaion is called a precipitation reaction, and the solid is called the precipitate. For example, when water solutions of calcium nitrate and sodium carbonate are mixed, calcium carbonate precipitates from the solution while the other product, sodium nitrate, remains dissolved. 

In order to predict whether a precipitation reaction will take place when two aqueous ionic compounds are mixed, you need to be able to predict whether the possible products of the double-displacement reaction are soluble or insoluble in water. 

These double-displacement reactions have two major features in common. First, two compotmds exchange ions or elements to form new compounds. Second, one of the products is either a compound that will separate from the reaction mixture in some way (commonly as a sohd or gas) or a stable covalent compotmd, often water. 

A neutralization reaction is a double-displacement reaction of an acid and a base. Acids are compounds that can release hydrogen ions bases are com-poxmds that can neutrafize acids by reacting with hydrogen ions. The most common bases are hydroxide and oxide compounds of the metals. Normally, an acid reacts with a base to form a salt and water. Neutrafization reactions occur because of the formation of the very stable covalent water molecule, H2O, from hydrogen and hydroxide ions. 

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