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julia-pushkina [17]
3 years ago
7

Which explains the basis of the Biuret test? a. Under base conditions, copper ions bind to the amino groups of proteins and chan

ge color. b. Iodine fits into the coils of starch polymers and changes color. c. A blue dye binds to protein and changes color.d. Sudan III dye binds to lipids and changes color.

Chemistry
2 answers:
nasty-shy [4]3 years ago
7 0

Answer:Answer: Under base conditions, copper ions bind to amino groups of proteins and change colour.

Explanation: Biuret test is a general test for detecting the presence of a peptide bond in a compound. It is a test for proteins. Amino acids are joined together in proteins by peptide bonds. Copper ions from blue alkaline solution of CuSO4 react with amino groups of proteins to give a violet colored complex called a biuret compound

Ugo [173]3 years ago
3 0

Answer:A

Explanation:

In the Biuret test, the copper ions bind covalently to the amino groups as shown in the image to form a violet complex. This violet complex is responsible for the colour change as shown

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The decomposition of copper(II) nitrate on heating is endothermic reaction. 2Cu(NO3)2(s) → 2C10(s) + 4NO2(g) + O2(g) Calculate t
Basile [38]

Answer:

The enthalpy change for the given reaction is 424 kJ.

Explanation:

2Cu(NO_3)_2(s)\rightarrow 2CuO(s) + 4NO_2(g) + O_2(g),\Delta H_{rxn}=?

We have :

Enthalpy changes of formation of following s:

\Delta H_{f,Cu(NO_3)_2}=-302.9 kJ/mol

\Delta H_{f,CuO}=-157.3 kJ/mol

\Delta H_{f,NO_2}= 33.2 kJ/mol

\Delta H_{f,O_2}= 0 kJ/mol (standard state)

\Delta H_{rxn}=\sum [\Delta H_f(product)]-\sum [\Delta H_f(reactant)]

The equation for the enthalpy change of the given reaction is:

\Delta H_{rxn} =

=(2 mol\times \Delta H_{f,CuO}+4\times \Delta H_{f,NO_2}+1 mol\times \Delta H_{f,O_2})-(2mol\times \Delta H_{f,Cu(NO_3)_2})

\Delta H_{rxn}=

(2mol\times (-157.3 kJ/mol)+4\times 33.2 kJ/mol=1 mol\times 0 kJ/mol)-(2 mol\times (-302.9 kJ/mol)

\Delta H_{rxn}=424 kJ

The enthalpy change for the given reaction is 424 kJ.

6 0
3 years ago
The volume of a pond being studied for the effects of acid rain is 35 kiloliters (kL). There are 1,000 liters (L) in 1 kL and 1
Lerok [7]

Answer:

35,000,000,000 mL

Explanation:

You first multiply 35 times 1000.

35,000 L

Now you multiply 35,000 times 10^6

35,000,000,000 mL

4 0
3 years ago
Why does the density of a substance stay constant even if the mass of the substance increases?
olganol [36]

Answer:

If the mass stays constant the object's density decreases as the volume increases. ... Because the property of density is a constant for all variables, density can be used to identify the material an object is made of.

Explanation:

5 0
3 years ago
How many moles are in a 12.0 g sample of NiC12
Nady [450]

Answer:

0.17 moles

Explanation:

In the elements of the periodic table, the atomic mass = molar mass. <u>Ex:</u> Atomic mass of Carbon is 12.01 amu which means molar mass of Carbon is also 12.01g/mol.

In order to find the # of moles in a 12 g sample of NiC-12, we will need to multiply the number of each atom by its molar mass and then add the masses of both Nickel and C-12 found in the periodic table:

  • Molar Mass of Ni (Nickel): 58.69 g/mol
  • Molar Mass of C (Carbon): 12.01 g/mol

Since there's just one atom of both Carbon and Nickel, we just add up the masses to find the molar mass of the whole compound of NiC-12.

  • 58.69 g/mol of Nickel + 12.01 g/mol of Carbon = 70.7 g/mol of NiC-12

There's 12g of NiC-12, which is less than the molar mass of NiC-12, so the number of moles should be less than 1. In order to find the # of moles in NiC-12, we need to do some dimensional analysis:

  • 12g NiC-12 (1 mol of NiC-12/70.7g NiC-12) = 0.17 mol of NiC-12
  • The grams cancel, leaving us with moles of NiC-12, so the answer is 0.17 moles of NiC-12 in a 12 g sample.

<em>P.S. C-12 or C12 just means that the Carbon atom has an atomic mass of 12amu and a molar mass of 12g/mol, or just regular carbon.</em>

5 0
3 years ago
For the reaction PC15 (8) PC13 (g) + Cl2 (g) K = 0.0454 at 261 °C. If a vessel is filled with these gases such that the initial
Fiesta28 [93]

Answer:

The correct answer is B.

The K_{eq} is samller than Q of the reaction . So,the reaction will shift towards the left i.e. towards the reactant side.

Explanation:

Equilibrium constant is defined as the ratio of concentration of products to the concentration of reactants each raised to the power their stoichiometric ratios. It is expressed as K_{eq}

K is the constant of a certain reaction when it is in equilibrium, while Q is the quotient of activities of products and reactants at any stage other than equilibrium of a reaction.

For the given chemical reaction:

PCl_5(g)\rightleftharpoons PCl_3(g)+Cl_2(g)

The expression for Q is written as:

Q=\frac{[PCl_3][Cl_2]}{[[PCl_5]^1}

Q=\frac{0.20 M\times 2.5 M}{0.20 M}

Q=2.5

Given : K_{eq} = 0.0454

Thus as K_{eq}, the reaction will shift towards the left i.e. towards the reactant side.

4 0
3 years ago
Read 2 more answers
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