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3 years ago

Which of the following is NOT a qualitative observation

Chemistry

1 answer:

frozen [14]3 years ago

4 0

what is the following???

a qualitative observation is when somehthings appearance changes like form red to blue, and qualitative is when the umber of something changes.

Hope this helps

Kenny

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Which product is not made from a renewable resource? select one:

Lady bird [3.3K]

The answer is B plastic bags made from petroleum.

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3 years ago

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Which model of the atom was used as a result of JJ Thomson's cathode ray

mariarad [96]

Answer:

a. Plum pudding model

Explanation:

The plum pudding model of the atom was proposed by J.J. Thomson. It was the model he derived from his experiment on the gas discharge tube.

J.J Thomson was the first person to discover electrons which he called cathode rays because in the discharge tube, they emanate from the cathode.

This led him to suggest the plum pudding model of the atom.
The model reflects electrons being surrounded by a volume of negative charges.

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3 years ago

Find percent yield:

saveliy_v [14]

Answer: The percent yield of the reaction is 91.8 %

Explanation:

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

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

For $B_5H_9$ :

Given mass of $B_5H_9$ = 4.0 g

Molar mass of $B_5H_9$ = 63.12 g/mol

Putting values in equation 1, we get:

$\text{Moles of }B_5H_9=\frac{4g}{63.12g/mol}=0.0634mol$

For oxygen gas:

Given mass of oxygen gas = 10.0 g

Molar mass of oxygen gas = 32 g/mol

Putting values in equation 1, we get:

$\text{Moles of oxygen gas}=\frac{10g}{32g/mol}=0.3125mol$

The chemical equation for the reaction of $B_5H_9$ and oxygen gas follows:

$2B_5H_9+12O_2\rightarrow 5B_2O_3+9H_2O$

By Stoichiometry of the reaction:

12 moles of oxygen gas reacts with 2 moles of $B_2H_5$

So, 0.3125 moles of oxygen gas will react with = $\frac{2}{12}\times 0.3125=0.052mol$ of $B_2H_5$

As, given amount of $B_2H_5$ is more than the required amount. So, it is considered as an excess reagent.

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

By Stoichiometry of the reaction:

12 moles of oxygen gas produces 5 moles of $B_2O_3$

So, 0.3125 moles of oxygen gas will produce = $\frac{5}{12}\times 0.3125=0.130moles$ of water

Now, calculating the mass of $B_2O_3$ from equation 1, we get:

Molar mass of $B_2O_3$ = 69.93 g/mol

Moles of $B_2O_3$ = 0.130 moles

Putting values in equation 1, we get:

$0.130mol=\frac{\text{Mass of }B_2O_3}{69.63g/mol}\\\\\text{Mass of }B_2O_3=(0.130mol\times 69.63g/mol)=9.052g$

To calculate the percentage yield of $B_2O_3$ , we use the equation:

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

Experimental yield of $B_2O_3$ = 8.32 g

Theoretical yield of $B_2O_3$ = 9.052 g

Putting values in above equation, we get:

$\%\text{ yield of }B_2O_3=\frac{8.32g}{9.052g}\times 100\\\\\% \text{yield of }B_2O_3=91.8\%$

Hence, the percent yield of the reaction is 91.8 %

6 0

3 years ago

Ethylene glycol (antifreeze) has a density of 1.11 g/cm3. What is the mass in grams of 387 mL of ethylene glycol?

harkovskaia [24]

To start, 1 cubic centimeter = 1 milliliter, so now you have 1.11g/mL.

Now multiply 1.11 by 387 to get the mass of antifreeze in grams, since the mL is canceled out.

387 mL x 1.11g/mL = 429.57 g

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3 years ago

Lab report evidence of plate motion

iogann1982 [59]

Explanation:

There is variety of evidence that supports the claims that plate tectonics accounts for

(1) the distribution of fossils on different continents

,(2) the occurrence of earthquakes, and

(3) continental and ocean floor features including mountains, volcanoes, faults, and trenches.

MARK AS BRAINLIST IF IT IS USEFUL

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2 years ago