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Goryan [66]
3 years ago
15

A few drops of a mixture of sodium hydroxide(NaOH) solution and copper (II) tetraoxosulphate (VI) solution were added to a sampl

e of urine in a test tube.State the two possible results of the test.What corresponding inferences can be made from the results above?​

Chemistry
1 answer:
Kaylis [27]3 years ago
5 0

Answer:

It is a test for proteins in urine

Explanation:

The Biuret reagent is made of sodium hydroxide (NaOH) and hydrated copper(II) sulfate. The biuret reagent is commonly used to test for proteins. The biuret test is also known as Piotrowski's test. It is a chemical test commonly used in detecting the presence of peptide bonds. In the presence of peptides, a copper(II) ion forms purple-colored coordination complexes in an alkaline solution.

Hence the addition of this Biuret reagent to a urine sample in a test tube aims to detect the presence or absence of proteins in the given urine sample. If there is protein in the urine sample, the blue colour of the Biuret reagent turns purple. If there is no protein in the urine sample, the Biuret reagent remains blue.

In an alkaline solution, copper II is able to form a complex with the peptide bonds in proteins. Once this complex has been formed, the Biuret solution turns from a blue color to a purple color. This is the positive test for proteins.

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Calculate the number of chlorine atoms that are present in 66.05 g of dichloromethane, ch2cl2. when you have the number, take it
Whitepunk [10]
From the periodic table:
mass of carbon = 12 grams
mass of hydrogen = 1 gram
mass of chlorine = 35.5 grams
Therefore,
molar mass of CH2Cl2 = 12 + 2(1) + 2(35.5) = 85 grams

number of moles = mass / molar mass
number of moles of CH2Cl2 = 66.05 / 85 = 0.777 moles

One mole of CH2Cl2 contains two moles of Cl and each chlorine mole has Avogadro's number of atoms in it.
Therefore,
number of chlorine atoms in 0.777 moles of CH2Cl2 can be calculated as follows:
number of atoms = 0.777 * 2 * 6.022 * 10^23 = 9.358 * 10^23 atoms

Now, we will take log base 10 for this number:
log (9.358 * 10^23) = 23.97119
5 0
3 years ago
Calculate the new volume of 1.23 mL of a gas at 32 C is subjected to drop in temperature of 20 degrees Celsius
kotykmax [81]

Answer:

1,15mL = V₂

Explanation:

Based on Charle's law the volume is directely proportional to the absolute temperature in a gas under constant pressure. The equation is:

V₁T₂ = V₂T₁

<em>Where V is volume and T absolute temperature of a gas where 1 is initial state and 2, final state.</em>

The V₁ is 1.23mL

T₁ = 32°C + 273.15 = 305.15K

T₂ = T₁ - 20°C = 285.15K

Replacing:

1.23mL*285.15K = V₂*305.15K

<h3>1,15mL = V₂</h3>

<em />

8 0
2 years ago
Ca(OH)2 (s) precipitates when a 1.0 g sample of CaC2(s) is added to 1.0 L of distilled water at room temperature. If a 0.064 g s
Nina [5.8K]

Answer:

D) Ca(OH)₂ will not precipitate because Q <  Ksp

Explanation:

Here we have first a chemical reaction in which Ca(OH)₂  is produced:

CaC₂(s)  + H₂O ⇒ Ca(OH)₂ + C₂H₂

Ca(OH)₂  is slightly soluble, and depending on its concentration it may precipitate out of solution.

The solubility product  constant for Ca(OH)₂  is:

Ca(OH)₂(s) ⇆ Ca²⁺(aq) + 2OH⁻(aq)

Ksp = [Ca²⁺][OH⁻]²

and the reaction quotient Q:

Q = [Ca²⁺][OH⁻]²

So by comparing Q with Ksp we will be able to determine if a precipitate will form.

From the stoichiometry of the reaction we know the number of moles of hydroxide produced, and since the volume is 1 L the molarity will also be known.

mol Ca(OH)₂ = mol CaC₂( reacted = 0.064 g / 64 g/mol = 0.001 mol Ca(OH)₂

the concentration of ions will be:

[Ca²⁺ ] = 0.001 mol / L 0.001 M

[OH⁻] = 2 x 0.001 M  = 0.002 M  ( From the coefficient 2 in the equilibrium)

Now we can calculate the reaction quotient.

Q=  [Ca²⁺][OH⁻]² = 0.001 x (0.002)² = 4.0 x 10⁻⁹

Q < Ksp since 4.0 x 10⁻⁹ < 8.0 x 10⁻⁸

Therefore no precipitate will form.

The answer that matches is option D

8 0
3 years ago
Styrofoam has a density of 0.075 g/mL. What is the volume of 21.80 g of Styrofoam?
LekaFEV [45]

The answer is 290.66 mL

Explanation:

The density of any substance including styrofoam is determined by two main factors: mass (atoms in the substance) and volume (space occupied). Moreover, the volume or mass of the substance can be calculated by using the density as these variables are related. Below I show the process:

density = mass / volume

mass = density x volume

volume = mass / density

volume = 21.80 g / 0.075 g/mL

volume = 290.66 mL

4 0
3 years ago
A student heats a sample of hydrate once, and the mass of the sample and the evaporating dish is 16.428 g. After a second heatin
jolli1 [7]

Answer:

12.371 g

Explanation:

Given :

m_{evaporating\ dish}=1.135\ g

m_{evaporating\ dish}+m_{Hydrate\ sample}=25.637\ g

m_{evaporating\ dish}+m_{First\ heated\ sample}=16.428\ g

m_{evaporating\ dish}+m_{Second\ heated\ sample}=13.266\ g

Mass of salt hydrate:

m_{evaporating\ dish}=1.135\ g

m_{evaporating\ dish}+m_{Hydrate\ sample}=25.637\ g

m_{Hydrate\ sample}=25.637-m_{evaporating\ dish}\ g=25.637-1.135\ g=24.502\ g

Mass of salt anhydrous:

m_{evaporating\ dish}=1.135\ g

m_{evaporating\ dish}+m_{Second\ heated\ sample}=13.266\ g

m_{Second\ heated\ sample}=m_{salt\ anhydrous}=13.266-m_{evaporating\ dish}\ g=13.266-1.135\ g=12.131\ g

Mass of water:

m_{water}=m_{Hydrate\ sample}-m_{salt\ anhydrous}=24.502-12.131\ g=12.371\ g

m_{water}=12.371\ g

4 0
3 years ago
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