Unit 1 – Introduction to Sustainable Chemistry: Stoichiometry, Green Chemistry, and Metrics

Unit 1 – Introduction to Sustainable Chemistry

1.0 Chemistry – The Central Science

Chemistry is often referred to as the central science because it connects physical sciences with life sciences and applied sciences. Its applications are vital in health, energy, and environmental sectors.

• Chemistry's Role: Underpins advances in medicine, engineering, physics, materials science, and nuclear research.

• Current Trends: Focus on making chemistry safer and more sustainable for humans and the environment.

1.0 Unit Coverage

• 1.1 What is Sustainability?

• 1.2 What is Green Chemistry?

• 1.3 Green Chemistry Metrics

• 1.4 Putting it all Together

1.0 Unit Objectives

• Discuss the role of chemists in positive change.

• Examine sustainability through:

  • UN Sustainable Development Goals (SDGs)

  • 12 Principles of Green Chemistry

  • Life Cycle Assessment (LCA)

• Perform calculations in:

  • Stoichiometry

  • Gas laws

  • Green chemistry metrics: Atom Economy, E-Factor, Reaction Mass Efficiency

1.1 What is Sustainability?

Definition and Issues

Sustainability is defined as "meeting the needs of the present without compromising the ability of future generations to meet their own needs" (United Nations Brundtland Commission).

• Addresses issues such as resource depletion, pollution, and environmental degradation.

• Example: The Aral Sea has been drying up due to unsustainable water use for agriculture.

Example Table: Daily Water Use per Capita (L)

Country	Daily Water Use/Capita (L)
Turkmenistan	1,638
China	5,143
Guyana	1,523
Uzbekistan	4,752
Tajikistan	4,480
Kyrgyzstan	4,181
United States	1,790

1.1 Sustainable Chemistry in a Warming World

Chemists contribute to sustainability through innovations in energy, materials, and pollution reduction.

Headlines	Chemists' Contributions
Solar power	New photovoltaic materials to increase efficiency
Carbon capture	New methods to capture and sequester atmospheric CO2
Hydrogen fuel	Efficient catalysts for hydrogen production
Plastics/microplastics	Bio-based, biodegradable, recyclable plastics
Batteries	New battery chemistries to increase capacity, safety, recharge rate, battery life

1.1 Case Study – Ibuprofen

Ibuprofen: Synthesis and Sustainability

• Ibuprofen is a widely used NSAID (non-steroidal anti-inflammatory drug).

• Developed as a safer alternative to aspirin.

• Inhibits enzymes that produce prostaglandins (chemicals that trigger pain and inflammation).

• Case study focuses on making its synthesis more sustainable.

High School Chemistry/Fundamental Skills

• Balance chemical equations

• Use conversion factors and dimensional analysis

• Identify limiting and excess reactants

• Calculate theoretical and percent yield

• Apply the ideal gas law to stoichiometry problems

Example – Number of Atoms and Molecules

Given 125 g of C12H16O, calculate the number of molecules and carbon atoms.

• Molar Mass Calculation: $MM_{C_{12}H_{16}O} = 12 imes M_C + 16 imes M_H + M_O$ $MM_{C_{12}H_{16}O} = 12(12.01) + 16(1.008) + 16.00 = 176.25 ext{ g/mol}$

• Moles: $n = rac{m}{MM}$ $n = rac{125}{176.25} = 0.709 ext{ mol}$

• Molecules: $N_{molecules} = n imes N_A$ $N_{molecules} = 0.709 imes 6.022 imes 10^{23} = 4.27 imes 10^{23}$

• Carbon Atoms: $N_C = N_{molecules} imes 12 = 5.13 imes 10^{24}$

Example – Stoichiometry and Theoretical Yield

Calculate the theoretical yield of C13H18O in a reaction with 1.05 g of C16H22O3 and excess water.

• Moles of Reactant: $n_{C_{16}H_{22}O_3} = rac{1.05}{262.34} = 0.00400 ext{ mol}$

• Theoretical Yield: $n_{C_{13}H_{18}O} = n_{C_{16}H_{22}O_3}$ $m_{C_{13}H_{18}O} = n_{C_{13}H_{18}O} imes MM_{C_{13}H_{18}O}$ $m_{C_{13}H_{18}O} = 0.00400 imes 190.29 = 0.762 ext{ g}$

Example – Limiting Reagents and Percent Yield

Given masses of C13H19O and H3NO, determine the percent yield of C13H19NO.

• Limiting Reactant: $n_{C_{13}H_{19}O} = rac{115.25}{190.29} = 0.60656 ext{ mol}$ $n_{H_3NO} = rac{5.75}{33.03} = 0.174 ext{ mol}$

• Theoretical Yield: $m_{C_{13}H_{19}NO} = 0.174 imes 205.30 = 35.74 ext{ g}$

• Percent Yield: $ext{Percent Yield} = rac{ ext{actual yield}}{ ext{theoretical yield}} imes 100 ext{ ext{%}}$ $ext{Percent Yield} = rac{17.00}{35.74} imes 100 = 47.57 ext{ ext{%}}$

Example – Gas Laws in Stoichiometry

Calculate the volume of CO2 produced at 1.00 bar and 25°C from a reaction.

• Moles of CO2: $n_{CO_2} = 2.68 imes 10^{-3} ext{ mol}$

• Volume (Ideal Gas Law): $V = rac{nRT}{P}$ $V = rac{2.68 imes 10^{-3} imes 0.083145 imes 298}{1} = 0.0664 ext{ L}$

1.2 What is Green Chemistry?

Definition

Green Chemistry is a scientific approach that aims to reduce or eliminate the use and generation of hazardous substances in the design, manufacture, and application of chemical products.

• Focuses on sustainability, safety, and efficiency.

• Seeks to minimize environmental and human health impacts.

Implementation Goals

• Improved resource use

• Increased energy efficiency

• Reduced human health and environmental hazards

1.3 Green Chemistry Metrics

Atom Economy

Measures the efficiency of a chemical reaction in incorporating reactant atoms into the desired product.

• Formula: $ext{Atom Economy} = rac{ ext{Molar mass of desired product}}{ ext{Sum of molar masses of all reactants}} imes 100 ext{ ext{%}}$

• Higher atom economy means less waste.

Reaction Mass Efficiency (RME)

Ratio of the mass of the desired product to the total mass of reactants used, considering yield.

• Formula: $ext{RME} = rac{ ext{Mass of desired product}}{ ext{Total mass of reactants}} imes ext{Yield}$

E-Factor

Ratio of the total mass of waste produced to the mass of the desired product.

• Formula: $ext{E-Factor} = rac{ ext{Total mass of waste}}{ ext{Mass of desired product}}$

• Lower E-Factor indicates a greener process.

Comparison Table: Green Chemistry Metrics

Metric	Prior Synthesis	Current Synthesis
Atom Economy	50%	77%
RME	0.13	0.3
E-Factor	9x	3x

1.4 Putting it All Together

Life Cycle Assessment (LCA)

LCA evaluates the environmental impacts of a product or process from raw material extraction to disposal. It is essential for determining the overall sustainability of chemical processes.

• Considers resource use, energy consumption, emissions, and waste.

• Helps compare different processes to identify the "greener" option.

UN Sustainable Development Goals (SDGs)

Green chemistry supports several SDGs, including responsible consumption, climate action, and good health and well-being.

Summary

• Chemistry is central to solving sustainability challenges.

• Stoichiometry and gas laws are foundational tools for quantifying chemical processes.

• Green chemistry metrics (Atom Economy, RME, E-Factor) help assess and improve the sustainability of chemical syntheses.

• Life Cycle Assessment and alignment with SDGs ensure holistic evaluation of chemical processes.

Additional info: These notes expand on the original slides by providing full definitions, formulas, and context for each concept, making them suitable for exam preparation in General Chemistry.