There are many important laws and theories in science. Which of the following is a law of science?

What is the composition, in atom percent, of an alloy that consists of a) 5.5 wt% Pb and b) 94.5 wt% of Sn? Assume that the atom

Anastaziya [24]

Answer : The percent composition of Pb and Sn in atom is, 3.21 % and 96.8 % respectively.

Explanation :

First we have to calculate the number of atoms in 5.5 wt% Pb and 94.5 wt% of Sn.

As, 207.2 g of lead contains $6.022\times 10^{23}$ atoms

So, 5.5 g of lead contains $\frac{5.5}{207.2}\times 6.022\times 10^{23}=1.59\times 10^{22}$ atoms

and,

As, 118.71 g of lead contains $6.022\times 10^{23}$ atoms

So, 94.5 g of lead contains $\frac{94.5}{118.71}\times 6.022\times 10^{23}=4.79\times 10^{23}$ atoms

Now we have to calculate the percent composition of Pb and Sn in atom.

$\% \text{Composition of Pb}=\frac{\text{Atoms of Pb}}{\text{Atoms of Pb}+\text{Atoms of Sn}}\times 100$

$\% \text{Composition of Pb}=\frac{1.59\times 10^{22}}{(1.59\times 10^{22})+(4.79\times 10^{23})}\times 100=3.21\%$

and,

$\% \text{Composition of Sn}=\frac{\text{Atoms of Sn}}{\text{Atoms of Pb}+\text{Atoms of Sn}}\times 100$

$\% \text{Composition of Sn}=\frac{4.79\times 10^{23}}{(1.59\times 10^{22})+(4.79\times 10^{23})}\times 100=96.8\%$

Thus, the percent composition of Pb and Sn in atom is, 3.21 % and 96.8 % respectively.

6 0

2 years ago

Pyridine rings can also under electrophilic aromatic substitution. given 2-methoxypyridine below, draw the expected major produc

notka56 [123]

Co2 is correct buddy

8 0

2 years ago

A plot of velocity versus substrate concentration for a simple enzyme-catalyzed reaction produces a _____. This indicates that a

kirza4 [7]

Answer:

B) hyperbolic curve; saturated with substrate

Explanation:

Enzymatic kinetics studies the speed of enzyme catalyzed reactions. These studies provide direct information about the mechanism of the catalytic reaction and the specificity of the enzyme. The speed of a reaction catalyzed by an enzyme can be measured with relative ease, since in many cases it is not necessary to purify or isolate the enzyme. The measurement is always carried out under the optimal conditions of pH, temperature, presence of cofactors, etc., and saturating substrate concentrations are used. Under these conditions, the reaction rate observed is the maximum speed (Vmax). The speed can be determined either by measuring the appearance of the products or the disappearance of the reagents.

Following the rate of appearance of product (or disappearance of the substrate) as a function of time, the so-called reaction progress curve is obtained, or simply, the reaction kinetics. This curve is represented by a hyperbolic curve

5 0

2 years ago

You have four water samples at different temperatures. In which sample are the molecules vibrating at the fastest speed? A. wate

tatiyna

Answer:

99°C

Explanation:

asking questions is Best in life of education

4 0

2 years ago

The pKs of succinic acid are 4.21 and 5.64. How many grams of monosodium succinate (FW = 140 g/mol) and disodium succinate (FW =

Varvara68 [4.7K]

Answer:

9.744g of monosodium succinate.

4.925g of disodium succinate.

Explanation:

To find pH of the buffer produced by the mixture of monosodium succinate-Disodium succinate is obtained from H-H equation:

pH = pKa + log ([Na₂Suc] / [NaHSuc])

As you want a pH of 5.28 and pKa is 5.64:

5.28 = 5.64 + log ([Na₂Suc] / [NaHSuc])

-0.36 = log ([Na₂Suc] / [NaHSuc])

0.4365 = ([Na₂Suc] / [NaHSuc]) (1)

As total concentration of the buffer is 100mM = 0.100M:

0.100M = [Na₂Suc] + [NaHSuc] (2)

Replacing (2) in (1):

0.4365 = (0.100M - [NaHSuc] / [NaHSuc])

0.4365 [NaHSuc] = 0.100M - [NaHSuc]

1.4365 [NaHSuc] = 0.100M

[NaHSuc] = 0.0696M

And:

[Na₂Suc] = 0.0304M

As volume of the buffer is 1L:

[NaHSuc] = 0.0696 moles

[Na₂Suc] = 0.0304 moles

Using molar mass of both substances:

Mass of monosodium succinate:

0.0696moles * (140g / 1mol) = 9.744g of monosodium succinate.

Mass of disodium succinate:

0.0304moles * (162g / 1mol) = 4.925g of disodium succinate.

5 0

2 years ago