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2 years ago

Which of the following is a reason why a scientist might do research?

Chemistry

1 answer:

timurjin [86]2 years ago

6 0

Answer:

A scientist does research to make sure he has the right answers to his problems and correct numbers.

Explanation:

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(a) The absorbance of mixture at 400 nm was 0.40.

laiz [17]

Answer:

0.1 g/dl

Explanation:

The standard curve is a graph that relates the absorbance at 400 nm with the concentration of haemoglobin in mg/dl. To obtain the concentration from the absorbance value, we enter in the x-axis (absorbance at 400 nm) with the value 0.40 (the line between 0.2 and 0.6), we extrapolate the line to the curve and read the correspondent value on y-axis (concentration in mg/dl): 100 mg/dl.

So, we convert the concentration from mg/dl to g/dl by dividing into 1000:

100 mg/dl x 1 g/1000 mg = 0.1 g/dl

Therefore, the concentration of haemoglobin of the patient is 0.1 g/dl.

6 0

2 years ago

Which of the following would result in butyl phenyl ether as the major product? a. Reaction of phenoxide with 1-bromobutane b. R

AlladinOne [14]

Answer:

Reaction of 1-butanol with bromobenzene

Explanation:

The reaction would yield ether as the major product is the reaction of the 1-butanol with bromobenzene. This is because the reaction does not have the large percentage of the undesired side product. In fact, the major product is about 85 % in composition, compared to the 15 % of the minor product. Hence, the reaction is efficient.

4 0

3 years ago

When a student mixes 50 mL of 1.0 M HCl and 50 mL of 1.0 M NaOH in a coffee-cup calorimeter, the temperature of the resultant so

zmey [24]

Answer: 54.4 kJ/mol

Explanation:

First we have to calculate the moles of HCl and NaOH.

$\text{Moles of HCl}=\text{Concentration of HCl}\times \text{Volume of solution}=1.0M\times 0.05=0.05mole$

$\text{Moles of NaOH}=\text{Concentration of NaOH}\times \text{Volume of solution}=1.0\times 0.05L=0.05mole$

The balanced chemical reaction will be,

$HCl+NaOH\rightarrow NaCl+H_2O$

From the balanced reaction we conclude that,

As, 1 mole of HCl neutralizes by 1 mole of NaOH

So, 0.05 mole of HCl neutralizes by 0.05 mole of NaOH

Thus, the number of neutralized moles = 0.05 mole

Now we have to calculate the mass of water:

As we know that the density of water is 1 g/ml. So, the mass of water will be:

The volume of water = $50ml+50ml=100ml$

$\text{Mass of water}=\text{Density of water}\times \text{Volume of water}=1g/ml\times 100ml=100g$

Now we have to calculate the heat absorbed during the reaction.

$q=m\times c\times (T_{final}-T_{initial})$

where,

q = heat absorbed = ?

$c$ = specific heat of water = $4.18J/g^oC$

m = mass of water = 100 g

$T_{final}$ = final temperature of water = $27.5^0C$

$T_{initial}$ = initial temperature of metal = $21.0^0C$

Now put all the given values in the above formula, we get:

$q=100g\times 4.18J/g^oC\times (27.5-21.0)^0C$

$q=2719.6J=2.72kJ$

Thus, the heat released during the neutralization = 2.72 KJ

Now we have to calculate the enthalpy of neutralization per mole of $HCl$ :

0.05 moles of $HCl$ releases heat = 2.72 KJ

1 mole of $HCl$ releases heat = $\frac{2.72}{0.05}\times 1=54.4KJ$

Thus the enthalpy change for the reaction in kJ per mol of HCl is 54.4 kJ

6 0

2 years ago

Read 2 more answers

How many protons does hydrogen have?

Nataly_w [17]

Hello there!

Hydrogen has one proton because the number of protons in an atom is equal to the atomic number of the element. S ince hydrogen's atomic number is 1, it has one proton.

I hope that's help !

4 0

3 years ago

What do all nickel atoms have in common

Mama L [17]

All nickel atoms would have the same number of protons or atomic number.

4 0

3 years ago