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3 years ago

What effect does observing a substance's physical properties have on the substance?

1 answer:

8 0

There is no effect. When you observe a substance's physical properties, you're not doing anything that would catalyze a chemical change. For example, you most often observe with your eyes, and/or, if safe, you waft the substance's smell to your nose. Neither of these observations will effect the substance's physical properties.

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Caffeine is a compound found in some natural coffees and teas and in some colas. a. Determine the empirical formula for caffeine

andrey2020 [161]

Answer: The molecular formula will be $C_8N_4H_{10}O_2$

Explanation:

Mass of C= 49.47 g

Mass of N = 28.85 g

Mass of O = 16.48 g

Mass of H = 5.20 g

Step 1 : convert given masses into moles.

Moles of C = $\frac{\text{ given mass of C}}{\text{ molar mass of C}}= \frac{49.47g}{12g/mole}=4.12moles$

Moles of N = $\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{28.85g}{14g/mole}=2.06moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{16.48g}{16g/mole}=1.03moles$

Moles of H = $\frac{\text{ given mass of H}}{\text{ molar mass of H}}= \frac{5.20g}{1g/mole}=5.20moles$

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C = $\frac{4.12}{1.03}=4$

For N = $\frac{2.06}{1.03}=2$

For O = $\frac{1.03}{1.03}=1$

For H = $\frac{5.20}{1.03}=5$

The ratio of C : N: O: H = 4: 2: 1: 5

Hence the empirical formula is $C_4N_2OH_5$

The empirical weight of $C_4N_2OH_5$ = 4(12)+2(14)+1(16)+5(1)= 97 g.

The molecular weight = 194.19 g/mole

Now we have to calculate the molecular formula.

$n=\frac{\text{Molecular weight}}{\text{Equivalent weight}}=\frac{194.19}{97}=2$

The molecular formula will be = $2\times C_4N_2H_5O=C_8N_4H_{10}O_2$

5 0

3 years ago

What are bonds in metals like?<br> (K12)

elena-s [515]

Answer:

Metallic bonds are the force of attraction between positive metal ions and the valence electrons that are constantly moving around them. The ions form a lattice-like structure held together by the metallic bonds. Metallic bonds explain why metals can conduct electricity and bend without breaking.

Explanation:

8 0

3 years ago

Read 2 more answers

How many hydrogen atoms are represented in the formula (CH3)2CH2?

SCORPION-xisa [38]

7 ..... i think because in CH3 there would be 3 H atoms while in 2CH2 there would be four

5 0

4 years ago

The jewelers' mass unit for diamond is the

maria [59]

Answer:

0.75 cm

Explanation:

You will convert 1.07 carat into mg then into g. You will multiply its reciprocal by 3.51g/cm to get the answer.

3 0

3 years ago

Match the element with its description. Match Term Definition Potassium A) Great conductor of heat and electricity Barium B) Mal

mezya [45]

<span>Barium - A) Great conductor of heat and electricity Potassium - B) Malleable and highly reactive Boron - C) Has properties of both metals and nonmetals Neon - D) Nonreactive gas Let's look at each element and it's place on the periodic chart to see what matches. Potassium - This is on the far left column for alkali metals. This means it's highly reactive and since it's a metal, it's both malleable and conductive. Looking at the available options, "B) Malleable and highly reactive" is the best choice. Barium - This element is in the second column from the left, so it's a fairly reactive metal, but not nearly as reactive as Potassium above. So "A) Great conductor of heat and electricity" is the best choice here, although I wouldn't call it "great". The resistivity of barium is about 20 times larger than copper. Boron - This element is about in the middle of the periodic chart, so it does have the properties of both metals and nonmetals. So "C) Has properties of both metals and nonmetals" is the best choice. Neon - This is in the far right column for noble gasses. Very non-reactive. So "D) Nonreactive gas" is the best choice.</span>

5 0

4 years ago