How to Make Hydrogen Sulfate
Hydrogen sulfate is a common chemical made in the chemistry laboratory. It has several notable chemical properties, such as its ability to react as either an acid or a base and its relationship to sulfuric acid as its conjugate base. These properties make hydrogen sulfate (also known as bisulfate) a useful chemical to synthesize. It is widely used as a food additive and a pH control chemical in pools. With the reaction of two widely available chemicals—sodium chloride and sulfuric acid—hydrogen sulfate can be made in even the most basic laboratory.
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Things You'll Need
- Two beakers
- Lab-grade sodium chloride
- Sulfuric acid
- Water
- Mass balance
- Fume hood
- Weighing paper
- Hot plate
- Thermometer
- Calculator
- Laboratory goggles
- Lab apron or lab coat
- Closed-toed shoes
Instructions
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Preparatory Calculations and Obtaining Reagents
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1
Decide which salt of hydrogen sulfate to make. Hydrogen sulfate is an ion with a single negative charge, so it is only stable with a positive ion, such as lithium, sodium or potassium. The following example will use sodium, the most common choice.
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2
Determine how much sodium hydrogen sulfate you wish to synthesize, in grams.
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3
Calculate the number of moles represented by the number of grams of hydrogen sulfate you plan to make. The molar mass of sodium hydrogen sulfate is 120.06 g/mol. Divide the number of grams you plan to produce by 120.06 g/mol to obtain the moles of sodium hydrogen sulfate.
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4
Calculate the moles needed of sulfuric acid and sodium chloride to make the product. One mole of sodium chloride reacts with one mole of sulfuric acid to form one mole of product. Therefore, the moles of sulfuric acid and sodium chloride equal the moles calculated in Step 3.
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5
Multiply the molar masses of sodium chloride (58.44 g/mol) and sulfuric acid (98.08 g/mol) by the respective moles of each (calculated in Step 4) to determine exactly how many grams of each reactant you will need.
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6
Purchase at least as many grams of lab-grade sodium chloride and sulfuric acid as you previously calculated. The reagents can be found online or can be purchased through chemical companies, or they may already be available in your laboratory.
Running the Reaction
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7
Don all of your safety gear. Be sure to wear a lab coat or lab apron, goggles and closed-toed shoes at all times in the laboratory.
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8
Measure the exact amount in grams of sodium chloride and sulfuric acid you previously calculated on a mass balance with weighing paper. Add the sodium chloride and sulfuric acid to separate beakers.
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9
Add a minimal, but sufficient, amount of water to the beaker with the sulfuric acid. Determine how much to add by adding the water in small increments very slowly, swirling the beaker to help it dissolve, and checking to see if any undissolved crystals remain. Stop adding water when the sulfuric acid appears to be fully dissolved.
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10
Locate a fume hood in the laboratory and make sure it is turned on. Add the sodium chloride to the sulfuric acid beaker slowly under the fume hood, and place it on the hot plate. Watch for the formation of sodium hydrogen sulfate, which should appear as a molten solid.
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11
After the reaction appears to proceed no further or no more product is made, increase the heat setting on the hot plate to boil off residual water. Check the temperature with a thermometer; it should be above 100º centigrade.
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12
Cover the top of the reaction beaker, and let the product cool. Then, if available, spray the product with an air sprayer to remove all traces of water before storage.
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13
Transfer the final product from the reaction beaker into a sealed, dry bottle.
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1
Tips & Warnings
If you want to create a different bisulfate salt besides sodium hydrogen sulfate, choose a different ionic salt than NaCl whose cation matches the product. For example, to make potassium hydrogen sulfate, use potassium chloride instead, and adjust the mole calculations in Section 1 as necessary.
Avoid touching the sulfuric acid at any time. It is a strong acid and can cause severe burns.
Never perform the reaction outside a fume hood. A side product of the reaction is gaseous hydrochloric acid, which is an eye and respiratory irritant.
Do not touch the surface of the hot plate until it has cooled after the reaction.
References
Resources
- Photo Credit salt image by Andrey Rakhmatullin from Fotolia.com
