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3 years ago

A teacher wants to perform a classroom demonstration that illustrates both chemical and physical changes. Which

Chemistry

2 answers:

wariber [46]3 years ago

5 0

It would be dissolving sugar in water/burning a candle

NeX [460]3 years ago

3 0

Answer:

dissolving sugar in water

burning a candle

Explanation: these both have chemical and physical changes happening to them.

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How would you solve this?

Lubov Fominskaja [6]

I’m sorry but I did not understand the question

6 0

3 years ago

Iron has a density of 7.86g/cm^3. Could a block of metal with a mass of 18.2g and a volume of 2.56cm^3 be iron? Show work and ex

hjlf

First calculate density of the the metal (should equal to density of iron)

Mass=18.2g
Volume=2.56cm^3

$\\ \bull\tt\longmapsto Density=\dfrac{Mass}{Volume}$

$\\ \bull\tt\longmapsto Density=\dfrac{18.2}{2.56}$

$\\ \bull\tt\longmapsto Density=7.1g/cm^3$

Metal is not iron

5 0

2 years ago

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During studies of the reaction below,

Leni [432]

Answer: The percent yield of the nitrogen gas is 11.53 %.

Explanation:

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

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

For NO:

Given mass of NO = 11.5 g

Molar mass of NO = 30 g/mol

Putting values in equation 1, we get:

$\text{Moles of NO}=\frac{11.5g}{30g/mol}=0.383mol$

For $N_2O_4$ :

Given mass of $N_2O_4$ = 102.1 g

Molar mass of $N_2O_4$ = 92 g/mol

Putting values in equation 1, we get:

$\text{Moles of }N_2O_4=\frac{102.1g}{92g/mol}=1.11mol$

For the given chemical reactions:

$2N_2H_4(l)+N_2O_4(l)\rightarrow 3N_2(g)+4H_2O(g)$ ......(2)

$N_2H_4(l)+2N_2O_4(l)\rightarrow 6NO(g)+2H_2O(g)$ .......(3)

Calculating the experimental yield of nitrogen gas:

By Stoichiometry of the reaction 3:

6 moles of NO is produced from 2 moles of $N_2O_4$

So, 0.383 moles of NO will be produced from = $\frac{2}{6}\times 0.383=0.128mol$ of $N_2O_4$

By Stoichiometry of the reaction 2:

1 mole of $N_2O_4$ produces 3 moles of nitrogen gas

So, 0.128 moles of $N_2O_4$ will produce = $\frac{3}{1}\times 0.128=0.384mol$ of nitrogen gas

Now, calculating the experimental yield of nitrogen gas by using equation 1, we get:

Moles of nitrogen gas = 0.384 moles

Molar mass of nitrogen gas = 28 g/mol

Putting values in equation 1, we get:

$0.384mol=\frac{\text{Mass of nitrogen gas}}{28g/mol}\\\\\text{Mass of nitrogen gas}=(0.384mol\times 28g/mol)=10.75g$

Calculating the theoretical yield of nitrogen gas:

By Stoichiometry of the reaction 2:

1 mole of $N_2O_4$ produces 3 moles of nitrogen gas

So, 1.11 moles of $N_2O_4$ will produce = $\frac{3}{1}\times 1.11=3.33mol$ of nitrogen gas

Now, calculating the theoretical yield of nitrogen gas by using equation 1, we get:

Moles of nitrogen gas = 3.33 moles

Molar mass of nitrogen gas = 28 g/mol

Putting values in equation 1, we get:

$3.33mol=\frac{\text{Mass of nitrogen gas}}{28g/mol}\\\\\text{Mass of nitrogen gas}=(3.33mol\times 28g/mol)=93.24g$

To calculate the percentage yield of nitrogen gas, we use the equation:

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

Experimental yield of nitrogen gas = 10.75 g

Theoretical yield of nitrogen gas = 93.24 g

Putting values in above equation, we get:

$\%\text{ yield of nitrogen gas}=\frac{10.75g}{93.24g}\times 100\\\\\% \text{yield of nitrogen gas}=11.53\%$

Hence, the percent yield of the nitrogen gas is 11.53 %.

7 0

3 years ago

Which methods would be suitable for determining the concentration of an aqueous solution of KMnO4? I. Visible spectrophotometry

Elodia [21]

Answer:

Explanation:

Since the solution have an observable color, that means that it absorbs light in the visible region hence it can be determined by colorimetry. Secondly, KMnO4 is a reducing agent which can be titrated against an oxidizing agent and it's concentration accurately determined.

3 0

3 years ago

What is the density of an object having a volume of 8 ml and a mass of 22 grams?

solniwko [45]

Answer:

0.32gcm3 . I miss the old Kanye, straight from the 'Go Kanye

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Explanation:

5 0

3 years ago

Read 2 more answers