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Nata [24]
3 years ago
15

While performing the assays for the LDH kinetics experiment, you will pipet 25ul of 250 ug/ml LDH into 975 ul of assay buffer (T

ris, Lactate, and NAD). What is the final concentration of LDH in the assay?
Chemistry
1 answer:
ArbitrLikvidat [17]3 years ago
6 0

Answer:

6.25 μg/mL

Explanation:

When a dilution is made, the mass of the solute is conserved (Lavoiser's law), so the mass pipetted will be the mass in the assay. The mass is the concentration (C) multiplied by the volume (V). If the pipet solution is called 1, and the assay 2:

m1 = m2

C1*V1 = C2*V2

C1 = 250 μg/mL

V1 = 25 μL

V2 = 975 μL + 25 μL = 1000 μL (is the final volume of the assay after the addition of LDH)

250*25 = C2*1000

C2 = 6.25 μg/mL

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How much heat is needed to raise the temperature of water with mass of 27.0 g at 20.0°C to 45.0°C?
ohaa [14]

Answer:

2835 J

Explanation:

Take the specific heat capacity of water as 4.2 J/ g°C.

Energy (heat) = mass x specific heat capacity x change in temperature

(E= mcΔT)

E = 27 x 4.2 x (45-20)

E = 2835 J

7 0
3 years ago
Which of these is a chemical property?
ankoles [38]

Answer:

The second choice, or flammability.

Explanation:

The flammability of something is how easy it is for it to burn or ignite.

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cupoosta [38]
The answer is glycolsis, I'm pretty sure.
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What does the mole ratio represent
Drupady [299]

Answer:

A mole ratio is a conversion factor that relates the amounts in moles of any two substances in a chemical reaction

Explanation:

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3 years ago
Aspirin can be made in the laboratory by reacting acetic anhydride (C 4H 6O 3) with salicylic acid (C 7H 6O 3) to form aspirin (
Anastasy [175]

<u>Answer:</u> The percent yield of the aspirin is 77.5 %.

<u>Explanation:</u>

To calculate the mass of acetic anhydride, we use the equation:

\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}

Density of acetic anhydride = 1.08 g/mL

Volume of acetic anhydride = 2.80 mL

Putting values in above equation, we get:

1.08g/mL=\frac{\text{Mass of acetic anhydride}}{2.80mL}\\\\\text{Mass of acetic anhydride}=(1.08g/mL\times 2.80mL)=3.024g

To calculate the number of moles, we use the equation:

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}     .....(1)

  • <u>For acetic anhydride:</u>

Given mass of acetic anhydride = 3.024 g

Molar mass of acetic anhydride = 102.1 g/mol

Putting values in equation 1, we get:

\text{Moles of acetic anhydride}=\frac{3.024g}{102.1g/mol}=0.0296mol

  • <u>For salicylic acid:</u>

Given mass of salicylic acid = 1.24 g

Molar mass of salicylic acid = 138.12 g/mol

Putting values in equation 1, we get:

\text{Moles of salicylic acid}=\frac{1.24g}{138.12g/mol}=0.0089mol

The chemical equation for the combustion of hexane follows:

C_4H_6O_3+C_7H_6O_3\rightarrow C_9H_8O_4+C_2H_4O_2

By Stoichiometry of the reaction:

1 mole of salicylic acid reacts with 1 mole of acetic anhydride

So, 0.0089 moles of salicylic acid will react with = \frac{1}{1}\times 0.0089=0.0089mol of acetic anhydride

As, given amount of acetic anhydride is more than the required amount. So, it is considered as an excess reagent.

Thus, salicylic acid is considered as a limiting reagent because it limits the formation of product.

By Stoichiometry of the reaction:

1 mole of salicylic acid produces 1 mole of aspirin

So, 0.0089 moles of salicylic acid will produce = \frac{1}{1}\times 0.0089=0.0089moles of aspirin

Now, calculating the mass of aspirin from equation 1, we get:

Molar mass of aspirin = 180.16 g/mol

Moles of aspirin = 0.0089 moles

Putting values in equation 1, we get:

0.0089mol=\frac{\text{Mass of aspirin}}{180.16g/mol}\\\\\text{Mass of aspirin}=(0.0089mol\times 180.16g/mol)=1.60g

  • To calculate the percentage yield of aspirin, we use the equation:

\%\text{ yield}=\frac{\text{Experimental yield}}{\text{Theoretical yield}}\times 100

Experimental yield of aspirin = 1.24 g

Theoretical yield of aspirin = 1.60 g

Putting values in above equation, we get:

\%\text{ yield of aspirin}=\frac{1.24g}{1.60g}\times 100\\\\\% \text{yield of aspirin}=77.5\%

Hence, the percent yield of the aspirin is 77.5 %.

7 0
3 years ago
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