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3 years ago

A. property is a characteristic of a pure substance that can be observed without changing the substance into some thing else

Chemistry

1 answer:

wlad13 [49]3 years ago

7 0

The answer is physical property.

Physical properties are the properties that does not require the substance changing into another substance, which is, chemical change. Physical properties are usually observable and measurable, such as melting points, density, odor, color etc. These does not require a chemical reaction to happen.

The opposite of physical property is chemical property, which is how the substance changes to another. Such as how sodium reacts with water to make sodium hydroxide and hydrogen.

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Which of the following represents a synthesis reaction?

bija089 [108]

Answer: a) 2H2 + O2 --> 2H2O

Explanation: 2 compounds are combining to form a new compound. The others have 2 substances as the end result and synthesis only produces one result (2H2O in this case)

6 0

3 years ago

Consider the malate dehydrogenase reaction from the citric acid cycle. Given the listed concentrations, calculate the free energ

Ahat [919]

<u>Answer:</u> The Gibbs free energy of the reaction is 21.32 kJ/mol

<u>Explanation:</u>

The chemical equation follows:

$\text{Malate }+NAD^+\rightleftharpoons \text{Oxaloacetate }+NADH$

The equation used to Gibbs free energy of the reaction follows:

$\Delta G=\Delta G^o+RT\ln K_{eq}$

where,

$\Delta G$ = free energy of the reaction

$\Delta G^o$ = standard Gibbs free energy = 29.7 kJ/mol = 29700 J/mol (Conversion factor: 1 kJ = 1000 J)

R = Gas constant = 8.314J/K mol

T = Temperature = $37^oC=[273+37]K=310K$

$K_{eq}$ = Ratio of concentration of products and reactants = $\frac{\text{[Oxaloacetate]}[NADH]}{\text{[Malate]}[NAD^+]}$

$\text{[Oxaloacetate]}=0.130mM$

$[NADH]=2.0\times 10^2mM$

$\text{[Malate]}=1.37mM$

$[NAD^+]=490mM$

Putting values in above expression, we get:

$\Delta G=29700J/mol+(8.314J/K.mol\times 310K\times \ln (\frac{0.130\times 2.0\times 10^2}{1.37\times 490}))\\\\\Delta G=21320.7J/mol=21.32kJ/mol$

Hence, the Gibbs free energy of the reaction is 21.32 kJ/mol

4 0

3 years ago

What SI unit would best be used to express the height of your classroom ceiling ?

chubhunter [2.5K]

Feet would be the best unit to use. Yards would work as well though.
Hope that helps!

7 0

3 years ago

What is the best definition of low electromagnetic energy?

inysia [295]

The best definition of low electromagnetic energy would be A. Low electromagnetic energy has long wavelengths and low frequency.

6 0

3 years ago

HClO4 acid solution has a concentration of 5 Molarity. Calculate the concentration of this solution in

Nutka1998 [239]

Answer:

1. Percentage by weight = 0.5023 = 50.23 %

2. molar fraction =0.153

Explanation:

We know that

Molar mass of HClO4 = 100.46 g/mol

So the mass of 5 Moles= 5 x 100.46

Mass (m)= 5 x 100.46 = 502.3 g

Lets assume that aqueous solution of HClO4 and the density of solution is equal to density of water.

Given that concentration HClO4 is 5 M it means that it have 5 moles of HClO4 in 1000 ml.

We know that

Mass = density x volume

Mass of 1000 ml solution = 1 x 1000 =1000 ( density = 1 gm/ml)

m'=1000 g

Percentage by weight = 502.3 /1000

Percentage by weight = 0.5023 = 50.23 %

We know that

molar mass of water = 18 g/mol

mass of water in 1000 ml = 1000 - 502.3 g=497.9 g

So moles of water = 497.7 /18 mole

moles of water = 27.65 moles

So molar fraction = 5/(5+27.65)

molar fraction =0.153

6 0

3 years ago