Li is an alkali metal and when it reacts with a strong acid like H2SO4, it can release hydrogen gas. Let us understand the reaction mechanism behind Li and H2SO4.
Li has higher standard reduction potential -3.401 EV which is so high that it is placed above hydrogen in the electrochemical series. Lithium can easily donate one electron and can reduce many organic molecules. Sulfuric acid is one of the strongest inorganic acids and it can oxidize many elements in chemistry.
The reaction between Li and H2SO4 requires no catalyst, temperature, or pressure. Let us discuss the mechanism of the reaction between sulfuric acid and lithium, the reaction enthalpy, the type of reaction, product formation, etc in the following part of the article.
1. What is the product of H2SO4 and Li?
Lithium sulfate is a major product formed when H2SO4 and Li are reacted together and hydrogen gas is liberated. Li is present in a higher position than hydrogen in the electrochemical series so the corresponding sulfate is formed.
H2SO4 + Li = Li2SO4 + H2
2. What type of reaction is H2SO4 + Li?
H2SO4 + Li reaction is an example of a single displacement reaction along with redox and precipitation reactions. Here, elements having higher reduction potential reacts with the acid molecule.
3. How to balance H2SO4 + Li?
H2SO4 + Li = Li2SO4 + H2 reaction is not balanced, we have to balance the equation in the following way,
- First, we label all the reactants and products by A, B, C, and D as there are only four molecules obtained for this reaction and the reaction looks like this: A H2SO4 + B Li = C Li2SO4 + D H2
- Equating all the coefficients for all the same type of elements by rearranging them
- After the rearrangement of all the coefficients of the same elements by their stoichiometric proportion we get, H = 2A = 2D, S = A = C, O = 4A = 4C, Li = B = 2C
- Using the Gaussian elimination and equating all the equations we get, A = 1, B = 2, C = 1, and D = 1, so the oxidation number of Li is +2 on both sides.
- Write the whole equation in the balanced form
- The overall balanced equation will be,
H2SO4 + 2Li = Li2SO4 + H2
4. H2SO4 + Li titration
To estimate the quantity of sulfur, we can perform a titration between Li and H2SO4
Apparatus used
We need a burette, conical flask, burette holder, volumetric flask, and beakers for this titration.
Titre and titrant
H2SO4 acts as a titrant which is taken in the burette and the molecule to be analyzed is Li which is taken in a conical flask.
Indicator
The whole titration is done in an acidic medium or acidic pH so the best suitable indicator will be phenolphthalein which gives perfect results for this titration at given pH.
Procedure
The burette was filled with standardized H2SO4 and Li was taken in a conical flask along with the respective indicator. H2SO4 is added dropwise to the conical flask and the flask was shaking constantly. After a certain time when the endpoint arrived, indicator changes its color and the reaction was done.
We repeat the titration several times for better results and then we estimate lithium as well as sulfate quantity by the formula V1S1 = V2S2.
5. H2SO4+ Li net ionic equation
The net ionic equation between H2SO4 + Li is as follows,
2H+ + SO42- + 2Li+ + 2e– = 2Li+ + SO42- + H2
- H2SO4 can be ionized to H+ and SO42- as it is a strong electrolyte.
- After that, Li release two electrons for Li+.
- After that, Li2SO4 dissociate into Li+ and SO42- and hydrogen gas remain intact.
6. H2SO4+ Li conjugate pairs
H2SO4 + Li conjugate pairs will be the corresponding de-protonated and protonated form of that particular species which are listed below-
- Conjugate pair of H2SO4 = SO42-
- Conjugate pair of H– = H2
7. H2SO4 and Li intermolecular forces
The intermolecular force present in H2SO4 is due to the strong electrostatic force between a proton and sulfate ions. Also due to polarity, Van der Waal’s attraction is present but in the case of H2, covalent force, as well as dipole interaction is present, and for LiSO4 only covalent force is present.
| Molecule | Acting force |
| H2SO4 | Electrostatic, van der waal’s Dipole interaction |
| Li | ionic, metallic bond |
| Li2SO4 | Columbia force, ionic interaction |
| H2 | Covalent, H-bonding |
8. H2SO4 + Li reaction enthalpy
H2SO4 + Li reaction enthalpy is -380 KJ/mol which can be obtained by the formula enthalpy of products – enthalpy of reactants, and here the change in enthalpy is negative.
| Molecule | Enthalpy (KJ/mol) |
| Li | 0 |
| H2SO4 | -814 |
| Li2SO4 | -1436 |
| H2 | +242 |
and Products
9. Is H2SO4 + Li a buffer solution?
The reaction between H2SO4 + Li gives a buffer solution of Li2SO4 and H2 and they can control the pH of the reaction.
10. Is H2SO4 + Li a complete reaction?
The reaction H2SO4 + Li is a complete reaction because it gives one complete product Li2SO4 along with H2 gas. The reaction takes some time to complete until all the reactants completely react with the products.
11. Is H2SO4 + Li an exothermic or endothermic reaction?
The reaction between H2SO4 + Li is exothermic in terms of thermodynamics first law. So, the reaction takes more energy and temperature from the surrounding which helps to complete the reaction, Where δH is always negative.
12. Is H2SO4 + Li a redox reaction?
H2SO4 + Li reaction is a redox reaction because in this reaction many elements get reduced and oxidized as hydrogen gets reduced and Li gets oxidized.
H2SO4 and Li Reaction
13. Is H2SO4 + Li a precipitation reaction
The reaction H2SO4 + Li is a precipitation reaction because Li2SO4 gets precipitated in the solution and is not soluble in the reaction mixture.
14. Is H2SO4 + Li reversible or irreversible reaction?
The reaction between H2SO4+ Li is irreversible because we get H2 gas as a product. When gas is formed during the reaction the entropy of the reaction increases and the equilibrium of the reaction shifts towards the right-hand side only.
15. Is H2SO4 + Li displacement reaction?
The reaction between H2SO4+ Li is an example of single displacement reaction because in the above reaction Li+ displaced H+ in H2SO4 and H2 gas becomes free from the reaction.
Conclusion
H2SO4 and Li reaction mainly give us lithium sulfate along with hydrogen gas so it is a commercially important reaction for the production of hydrogen gas. Also, the quantitative analysis of H2SO4 and Li gives the amount of lithium as well as sulfate in the respective sample.
Read more facts on H2SO4:
Hi……I am Biswarup Chandra Dey, I have completed my Master’s in Chemistry from the Central University of Punjab. My area of specialization is Inorganic Chemistry. Chemistry is not all about reading line by line and memorizing, it is a concept to understand in an easy way and here I am sharing with you the concept about chemistry which I learn because knowledge is worth to share it.