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2 years ago

L 1.4.2 Quiz: Scientific Practices

Chemistry

1 answer:

9966 [12]2 years ago

5 0

Answer:

O B. Experimental group

Explanation:

An experimental group is a test sample or the group that receives an experimental procedure. This group is exposed to changes in the independent variable being tested.

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1.Using the absorbance of the spinach extract and the equation of the trendline, determine the concentration of the extract solu

lys-0071 [83]

Answer:

Explanation:

From the given information:

We are to make use of the spinach absorbance extract which is the corrected absorbance (y) = 0.306

And also the trendline equation:

y = 1609x + 0.0055

where,

x = absorbance of the spinach extract.

∴

0.306 = 1609x + 0.0055

collecting the like terms

0.306 - 0.0055 = 1609x

0.3005 = 1609x

x = 0.3005/1609

x = 1.8676 × 10⁻⁴

x ≅ 0.0002 M

No. of grams for the chlorophyll can be computed as follows:

recall that:

molar mass of chlorophyll = 893.5 g/mol

the volume = 25ml = (25/1000) L = 0.025 L

∴

In spinach solution, the no. of grams for the chlorophyll:

= (0.0002) mol/L × (893.5 g/mol) × (0.025) L

= 0.0044675 g

≅ 0.0045 g

In the spinach, the concentration of chlorophyll = no of grams of chlorophyll/ mass of the spinach

= 4.5 mg/0.1876 g

= 23.987 mg/g

≅ 24 mg/g

4 0

3 years ago

7. A student titrated a 15.00-mL sample of a solution containing a weak, monoprotic acid with NaOH. The titration required 17.73

stellarik [79]

Answer: The concentration of the weak acid in the sample is 0.1224 M

Explanation:

The balanced chemical reaction is :

$HA+NaOH\rightarrow NaA+H_2O$

To calculate the volume of acid, we use the equation given by neutralization reaction:

$n_1M_1V_1=n_2M_2V_2$

where,

$n_1,M_1\text{ and }V_1$ are the n-factor, molarity and volume of acid which is $HA$

$n_2,M_2\text{ and }V_2$ are the n-factor, molarity and volume of base which is NaOH.

We are given:

$n_1=1\\M_1=?\\V_1=15.00mL\\n_2=1\\M_2=0.1036M\\V_2=17.73mL$

Putting values in above equation, we get:

$1\times M_1\times 15.00=1\times 0.1036\times 17.73\\\\M_1=0.1224$

Thus the concentration (in M) of the weak acid in the sample is 0.1224

4 0

3 years ago

Which of these could be caused by an increase in sunspots activity?

Burka [1]

Answer:

Sun spots are cooler spots on the sun so anything to cool off part of the sun would create a sunspot

Hope this helps and have a great day!

Explanation:

6 0

3 years ago

A catalyst of copper mixed with zinc oxide and alumina is used in industry for this production of methanol. Explain the function

arsen [322]

Answer:Copper oxide + Hydrogen → Copper + Water

Copper sulfate + Zinc → Zinc sulfate + copper

Aluminium + Copper chloride → Aluminium chloride + copper

Copper + Oxygen → Copper oxide

Explanation:

Chemical reactions involves chemical combination of compounds or elements as reactants to form other compounds or elements.

In this case, various reactants given will react exhibiting different types of chemical reactions to form products.

First reaction

Aluminium + Copper chloride → Aluminium chloride + Copper

This is a single displacement reaction in which aluminium which is a more reactive element than copper displaces copper from its salt.

Second reaction

Copper oxide + Hydrogen → Copper + water

It is another example of a single replacement reaction. Hydrogen displaces less reactive metals from their oxide to form water and the metal.

Third reaction

Copper sulfate + Zinc → Zinc sulfate + copper

It is another single replacement reaction.

Zinc is more reactive than copper and therefore replaces copper from its salt solution.

Fourth reaction

Copper + Oxygen → Copper oxide

It is a synthesis reaction.

A synthesis reaction is a reaction in which elements or small compounds combine to form single compound.

4 0

3 years ago

A certain radioactive isotope has a half-life of 5 days. If one is to make a table showing the half-life decay of a sample of th

Pepsi [2]

It will take 25 days for this substance to become 1gram from 32 grams.

<h3><u>Explanation</u>:</h3>

Radioactivity or radioactive decay is the process of formation of different element from one Radioactive element due to decay of the radioactive nucleus. The radioactive decay is a first order kinetic reaction. This reaction has a straight log C vs T graph.

Here in this particular reaction, the half life of the radioactive substance is 5 days. So within 5 days, the concentration of the substance becomes halved.

Now, in the sample the amount of substance present = 32 grams

The final amount of this sample = 1 grams.

So number of half lives needed for this decay = 5 half lives.

So number of days required for this decay = $5\times5$ =25.

So within 25 days, 32 grams of the substance becomes 1grams.

6 0

4 years ago