FREE Master of Chemistry: Analytical Chemistry Questions and Answers
The absorption behavior of solutions with concentration is explained by Beer Lambert law.
The Beer-Lambert law, also known as the Beer-Lambert-Bouguer law, describes the relationship between the absorbance of a solution and the concentration of the absorbing solute in the solution. The law states that the absorbance of a solution is directly proportional to the concentration of the solute and the path length of the light through the solution. The law is valid for solutions with low to moderate concentrations, typically less than 1 mMol (millimolar). For solutions with higher concentrations, the linearity of the Beer-Lambert law might break down due to issues such as self-absorption or interactions between solute particles at high concentrations.
The transmitted radiations are of the following types when the EMR radiations travel through the medium:
The intensity of the transmitted EMR depends on various factors, including the properties of the medium, the wavelength of the radiation, and the interactions between the radiation and the particles in the medium. In some cases, the intensity of the transmitted radiation may be reduced (low intensity) due to absorption or scattering in the medium, while in other cases, it may remain relatively unchanged (high intensity) if the medium is transparent to the specific wavelength of radiation.
The UV-VIS radiation's wavelength
UV-VIS radiation covers the ultraviolet (UV) and visible (VIS) regions of the electromagnetic spectrum. The wavelengths in this range are approximately 100 nm to 1000 nm (1 µm). The UV region spans from 100 nm to about 400 nm, while the VIS region ranges from about 400 nm to 1 µm. Different UV-VIS spectrophotometers cover various portions of this range depending on their design and application.
The method used to collect data in a standard UV, VIS, and NIR spectrophotometer
In the photometric mode, the spectrophotometer measures the absorbance or transmittance of light at a specific wavelength or over a range of wavelengths. The sample is exposed to light, and the amount of light absorbed or transmitted by the sample is measured by a detector. The data collected in this mode is used to generate a UV/VIS/NIR absorption or transmission spectrum, which provides information about the sample's chemical composition and concentration of absorbing species. Photometric mode is the most common mode of operation for UV/VIS/NIR spectrophotometers and is widely used in various fields, including chemistry, biology, pharmaceuticals, and environmental analysis.
What amount of solute is needed to prepare 300 ml of 0.8M CaCl2 (mol.wt:111 g/mol)?
To calculate the amount of solute (CaCl2) required to prepare 300 ml of a 0.8 M solution, we can use the formula:
Amount of solute (in moles) = Molarity × Volume (in liters)
Given:
Molarity (M) = 0.8 M
Volume (V) = 300 ml = 0.3 liters
Amount of solute (in moles) = 0.8 M × 0.3 liters = 0.24 moles
Now, we need to calculate the mass of the solute using the molar mass (mol. wt) of CaCl2:
Mass of solute (in grams) = Amount of solute (in moles) × Molar mass (mol. wt)
Molar mass of CaCl2 = 1 × (40.08 g/mol) + 2 × (35.45 g/mol) = 40.08 g/mol + 70.90 g/mol = 111 g/mol
Mass of solute (in grams) = 0.24 moles × 111 g/mol ≈ 26.64 grams
Therefore, approximately 26.64 grams of CaCl2 is required to prepare 300 ml of a 0.8 M solution.
From the stock solution of 10M, which will be the final volume, prepare 200ml of 6M solution.From the stock solution of 10M, which will be the final volume, prepare 200ml of 6M solution.From the stock solution of 10M, which will be the final volume, prepare 200ml of 6M solution.
To prepare a 6M solution from a 10M stock solution, we can use the dilution formula:
C1V1 = C2V2
Where:
C1 = Initial concentration (10M)
V1 = Initial volume (unknown, we are trying to find this)
C2 = Final concentration (6M)
V2 = Final volume (200ml)
Now, plug in the values:
(10M)V1 = (6M)(200ml)
Solving for V1:
V1 = (6M)(200ml) / 10M
V1 = 120ml
So, to prepare a 200ml 6M solution from a 10M stock solution, you need to take 120ml of the stock solution and then add water to bring the total volume up to 200ml.
The output of a photomultiplier tube is in the form of
A photomultiplier tube (PMT) is a highly sensitive light detector that converts incoming photons into an electrical signal. When photons strike the photocathode surface of the PMT, they cause the emission of electrons through the photoelectric effect. These emitted electrons are then accelerated and multiplied through a series of dynodes inside the PMT, resulting in a measurable current at the output of the device. The current generated is proportional to the intensity of the incoming light, making PMTs valuable for detecting low levels of light in various applications, such as in fluorescence spectroscopy, scintillation counting, and particle detectors.
Wavenumber produces vibrations in the "H" attached to "sp2" hybrid carbon.
Infrared (IR) spectroscopy is a technique used to study the vibrations of molecules. The stretching vibration of the "H" attached to 'sp2' hybrid carbon (such as in alkenes or aromatic compounds) typically occurs around 3100 cm-1 in the IR spectrum. This band is known as the C-H stretching vibration of an sp2 hybridized carbon-hydrogen bond.
UV vacuum region is
Vacuum UV (VUV) radiation has shorter wavelengths than those in the UV-visible region and falls within the range specified above. This region is called "vacuum" UV because many of these wavelengths are strongly absorbed by air and other common gases, and measurements often require the use of vacuum or special gas environments. The Vacuum UV region is of significant interest in spectroscopy, photochemistry, and semiconductor research, among other scientific fields.
Material for building grating
The correct answer is None of these, as there are various materials used in grating construction depending on the application and wavelength range.
The region of the finger print is
In IR spectroscopy, the fingerprint region is a range of wavenumbers where complex and unique vibrational patterns of a molecule occur. This region is usually between 1300 and 650 cm-1. It provides a characteristic "fingerprint" for each molecule, helping to identify and differentiate various compounds based on their specific vibrational modes.
The UV-spectral spectrophotometer's band width is in the range of
The spectral bandwidth refers to the range of wavelengths detected by the spectrophotometer at any given point during a measurement. In UV spectrophotometers, the bandwidth is usually set around 1 nm to ensure high-resolution measurements and accurate determination of absorbance peaks or features in the UV-Vis spectrum. Some advanced spectrophotometers might have variable bandwidth settings, allowing users to adjust the bandwidth according to their specific analytical requirements.
There are several primary vibrations for linear molecules, including
For linear molecules, there are three translational degrees of freedom (3) and two rotational degrees of freedom (2). Therefore, the total number of vibrational degrees of freedom (N) for linear molecules is 3N-5. This accounts for the fact that linear molecules have fewer vibrational modes compared to non-linear molecules. The formula 3N-5 is used to calculate the number of fundamental vibrations for linear molecules in molecular spectroscopy and vibrational analysis.
Spectrogram produced by spectroscopic measurements is the outcome of the
In spectroscopy, a spectrogram or spectrum is obtained by measuring the absorption or transmission of electromagnetic radiation (light) by a sample. When a sample is exposed to a range of wavelengths of light, it absorbs certain wavelengths depending on its chemical composition and molecular structure. The absorbed wavelengths correspond to specific vibrational, rotational, or electronic energy levels in the molecules present in the sample.
Oxalic acid's basicity is
Oxalic acid (H2C2O4) is a dicarboxylic acid, which means it contains two carboxyl (-COOH) groups. Each carboxyl group can donate one proton (H+), so oxalic acid can donate a total of two protons. This makes its basicity 2.
Which method is best for determining the phosphate concentration in egg shells?
Solvent extraction is a commonly used method for isolating and concentrating specific compounds from complex matrices. In the case of eggshells, phosphate can be extracted from the solid matrix using an appropriate solvent, which would dissolve the phosphate ions from the eggshell. The extracted phosphate can then be quantified using colorimetric methods or other analytical techniques.