Bulletin Board Ideas by Theme. Our Bulletin Board Ideas by Theme pages provide you with resources to help display your students' learning while keeping your classroom walls looking great all year long. Within each theme you will find fun and educational resources that are specific to the various topics covered within that theme. Several of the bulletin boards even include photos.
Background for the Kjeldahl determination of Organic Nitrogen. The Kjeldahl method is an analytical method for the determination of nitrogen in the trinegative state in certain organic compounds. The method was developed in 1883 by Johan Kjeldahl, a Danish chemist, and is used extensively in the determination of protein in foods, since protein is a macromolecule made up of nitrogen containing amino acids linked together.
Hertz. Hertz (abbreviated: Hz) is the standard unit of measurement used for measuring frequency. Since frequency is measured in cycles per second, one hertz equals one cycle per second. Hertz is used commonly used to measure wave frequencies, such as sound waves, light waves, and radio waves.For example, the average human ear can detect sound waves between 20 and 20,000 Hz. Sound waves close to 20 Hz have a low pitch and are called bass frequencies.ince frequency is measured in cycles per second, one hertz equals one cycle per second. Hertz is used commonly used to measure wave frequencies, such as sound waves, light waves, and radio waves. For example, the average human ear can detect sound waves between 20 and 20,000 Hz.