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3 years ago

Biuret reagent will indicate the presence of

1 answer:

5 0

Biuret reagent will indicate the presence of protein in a given sample. It is also known as the Piotrowski's test. This reagent consists of copper (II) sulfate and sodium hydroxide. It detects peptide bonds by the reaction of the copper ions in an alkaline solution. The copper ions would form violet colored complexes when peptide is present in the solution. From this test, concentration can be calculated since the intensity of the color depends on the amount of peptide bonds and according to the Beer-Lambert law concentration and the absorption of light is proportional. The concentration is calculated by a spectrophotometric technique at a wavelength of 540 nm.

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What is not a guideline required for a valid evidence test?

kirill115 [55]

I just took that quiz , it’s A

4 0

3 years ago

The diagram shows the process of the water cycle on Earth. Heat from the Sun causes water to evaporate: the liquid water turns i

astra-53 [7]

The diagram below shows the different aspects of the water cycle, such as how water is observed by plants and how it is carried around by the atmosphere.

The diagram relates to a cactus biome.

Cactuses are still plants,

We have several characteristics that make cactus a plant:

1. Photosynthesis

Unlike other plants that photosynthesize with their leaves, cacti do so with their stems. At night, they take in carbon dioxide, which is then used during the day.

2. The stem succulent

A cactus is classified as a succulent. In other terms, a succulent is a plant that has thick juicy stems or leaves that store water. A cactus stores its water in stems, and some species are adapted to arid areas.

3. Special skin surface

One attribute that makes cacti not lose a lot of water is the fact that they have waxy surfaces that prevent evaporation. Some species also have ribbed surfaces that prevent splitting even when the plant expands during desert rainstorms.

4. Cactus spines

Cacti have spines that protect them from being eaten by animals. The spines also act as insulation during the dry seasons.

How do cactuses survive in the desert?

A cactus is able to survive in the desert due to the following features:

It has long roots that go deep inside the soil for absorbing water.

Its leaves are in the form of spines to prevent water loss through transpiration.

Its stem is covered with a thick waxy layer to retain water.

This shows how cactuses can survive without water and this relates to what the diagram shows however, the diagram shows that rain takes a part in the water cycle, whereas for cactuses, they don't need much water due to their extreme adaptivity.

But there are some similarities too, for example cactuses are still plants so they still photosynthesise and give us oxygen and whatnot.

Forgive me if this is wrong, I tried my best <3 Have a great day

(Forgive me if this is too long just use the important part)

6 0

3 years ago

Read 2 more answers

The osmotic pressure of a solution containing 2.04 g of an unknown compound dissolved in 175.0 mLof solution at 25 ∘C is 2.13 at

kherson [118]

Answer: The molecular formula of the compound is $C_4H_{10}O_4$

Explanation:

To calculate the concentration of solute, we use the equation for osmotic pressure, which is:

$\pi=iMRT$

Or,

$\pi=i\times \frac{\text{Mass of solute}\times 1000}{\text{Molar mass of solute}\times \text{Volume of solution (in mL)}}\times RT$

where,

$\pi$ = osmotic pressure of the solution = 2.13 atm

i = Van't hoff factor = 1 (for non-electrolytes)

Given mass of compound = 2.04 g

Volume of solution = 175.0 mL

R = Gas constant = $0.0821\text{ L atm }mol^{-1}K^{-1}$

T = temperature of the solution = $25^oC=[273+25]=298K$

Putting values in above equation, we get:

$2.13atm=1\times \frac{2.04\times 1000}{\text{Molar mass of compound}\times 175.0}\times 0.0821\text{ L.atm }mol^{-1}K^{-1}\times 298K\\\\\text{Molar mass of compound}=\frac{1\times 2.04\times 1000\times 0.0821\times 298}{2.13\times 175.0}=133.9g/mol$

Calculating the molecular formula:

The chemical equation for the combustion of compound having carbon, hydrogen and oxygen follows:

$C_xH_yO_z+O_2\rightarrow CO_2+H_2O$

where, 'x', 'y' and 'z' are the subscripts of carbon, hydrogen and oxygen respectively.

We are given:

Mass of $CO_2=36.26g$

Mass of $H_2O=14.85g$

We know that:

Molar mass of carbon dioxide = 44 g/mol

Molar mass of water = 18 g/mol

For calculating the mass of carbon:

In 44 g of carbon dioxide, 12 g of carbon is contained.

So, in 36.26 g of carbon dioxide, $\frac{12}{44}\times 36.26=9.89g$ of carbon will be contained.

For calculating the mass of hydrogen:

In 18 g of water, 2 g of hydrogen is contained.

So, in 14.85 g of water, $\frac{2}{18}\times 14.85=1.65g$ of hydrogen will be contained.

Mass of oxygen in the compound = (22.08) - (9.89 + 1.65) = 10.54 g

To formulate the empirical formula, we need to follow some steps:

Step 1: Converting the given masses into moles.

Moles of Carbon = $\frac{\text{Given mass of Carbon}}{\text{Molar mass of Carbon}}=\frac{9.89g}{12g/mole}=0.824moles$

Moles of Hydrogen = $\frac{\text{Given mass of Hydrogen}}{\text{Molar mass of Hydrogen}}=\frac{1.65g}{1g/mole}=1.65moles$

Moles of Oxygen = $\frac{\text{Given mass of oxygen}}{\text{Molar mass of oxygen}}=\frac{10.54g}{16g/mole}=0.659moles$

Step 2: Calculating the mole ratio of the given elements.

For the mole ratio, we divide each value of the moles by the smallest number of moles calculated which is 0.659 moles.

For Carbon = $\frac{0.824}{0.659}=1.25\approx 1$

For Hydrogen = $\frac{1.65}{0.659}=2.5$

For Oxygen = $\frac{0.659}{0.659}=1$

Converting the mole fraction into whole number by multiplying the mole fraction by '2'

Mole fraction of carbon = (1 × 2) = 2

Mole fraction of oxygen = (2.5 × 2) = 5

Mole fraction of hydrogen = (1 × 2) = 2

Step 3: Taking the mole ratio as their subscripts.

The ratio of C : H : O = 2 : 5 : 2

The empirical formula for the given compound is $C_2H_5O_2$

For determining the molecular formula, we need to determine the valency which is multiplied by each element to get the molecular formula.

The equation used to calculate the valency is:

$n=\frac{\text{Molecular mass}}{\text{Empirical mass}}$

We are given:

Mass of molecular formula = 133.9 g/mol

Mass of empirical formula = 61 g/mol

Putting values in above equation, we get:

$n=\frac{133.9g/mol}{61g/mol}=2$

Multiplying this valency by the subscript of every element of empirical formula, we get:

$C_{(2\times 2)}H_{(5\times 2)}O_{(2\times 2)}=C_4H_{10}O_4$

Hence, the molecular formula of the compound is $C_4H_{10}O_4$

4 0

3 years ago

How many liters of 4M solution can be made using 100 grams of lithium bromide

uysha [10]

Molar mass of LiBr (mm )= 86.845 g/mol

Molarity ( M ) = 4 M

Mass of solute ( m ) = 100 g

Volume ( V ) = in liters ?

V = m / mm * M

V = 100 / 86.845 * 4

V = 100 / 347.38

V = 0.2875 L

hope this helps!.

5 0

3 years ago

When we destroy soil, it releases?

lord [1]

Answer:

Ch02

Explanation:

5 0

3 years ago