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3 years ago

Which of these is an indication that a chemical reaction has occurred?

Chemistry

2 answers:

Elena L [17]3 years ago

8 0

A change in color indicates a chemical reaction :)

lilavasa [31]3 years ago

5 0

D. a change in color of a substance

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People mine zinc metal for use as an anticorrosive, skin protectant, and in electrical components. Zinc mining involves using ch

ankoles [38]

C I’m pretty sure. I hope this helps

3 0

3 years ago

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An organic compound is 61.5% C, 2.56% H and 35.9% N by mass. 2.00 grams of this gas is entered into a 300.0 mL flask and heated

pashok25 [27]

Answer:

C₄H₂N₂

Explanation:

First we calculate the moles of the gas, using PV=nRT:

P = 2670 torr ⇒ 2670/760 = 3.51 atm

V = 300 mL ⇒ 300/1000 = 0.3 L

T = 228 °C ⇒ 228 + 273.16 = 501.16 K

3.51 atm * 0.3 L = n * 0.082atm·L·mol⁻¹·K⁻¹ * 501.16 K

n = 0.0256 mol

Now we calculate the molar mass of the compound:

2.00 g / 0.0256 mol = 78 g/mol

Finally we use the percentages given to calculate the empirical formula:

C ⇒ 78 g/mol * 61.5/100 ÷ 12g/mol = 4

H ⇒ 78 g/mol * 2.56/100 ÷ 1g/mol = 2

N ⇒ 78 g/mol * 35.9/100 ÷ 14g/mol = 2

So the empirical formula is C₄H₂N₂

6 0

3 years ago

Setting up a one-step unit conversion A student sets up the following equation to convert a measurement. (The ? stands for a num

Aneli [31]

Answer:

0.0008 m

Explanation:

We are given that 0.080 cm

We have to convert 0.080 cm into meter

To find the value of 0.080 cm in meter we are using unitary method

We know that

100 cm =1 m

1 cm = $\frac{1}{100} m$

Therefore, 0.080 cm = $\frac{1}{100}\times 0.080 m$

0.080 cm = $\frac{1}{100}\times \frac{80}{1000}m$

0.080 cm = $\frac{8}{10000}m$

0.08cm=0.0008 m

Hence, the value of 0.080 cm is equal to 0.0008 meter .

7 0

3 years ago

Suppose that Daniel has a 3.00 3.00 L bottle that contains a mixture of O 2 O2 , N 2 N2 , and CO 2 CO2 under a total pressure of

Alenkinab [10]

Answer:

Partial pressure O₂ → 2.74 atm

Explanation:

Let's analyse the data given:

Volume → 3L

In the bottle there is a mixture of gases that contains, O₂, N₂ and CO₂.

Total pressure is 4.80 atm

Let's apply the Ideal Gases Law to determine the total moles of the mixture

P . V = n . R. T

4.80 atm . 3L = n . 0.082 . 273K

n = 4.80 atm . 3L / 0.082 . 273K → 0.643 moles

We apply the concept of mole fraction:

Mole fraction of a gas X = moles of gas X / Total moles

Mole fraction of a gas X = Partial pressure X / Total pressure

In a mixture, sum of mole fraction of each gas = 1

We determine mole fraction of N₂ → 0.230 / 0.643 = 0.357

We determine mole fraction of CO₂ → 0.350 atm / 4.80 atm = 0.0729

1 - mole fraction N₂ - mole fraction CO₂ = mole fraction O₂

1 - 0.357 - 0.0729 = 0.5701 → mole fraction O₂

We replace in the formula: Mole fraction O₂ = Partial pressure O₂ / 4.80 atm

0.5701 . 4.80 atm = Partial pressure O₂ → 2.74 atm

5 0

3 years ago

Read 2 more answers

Electromagnetic radiation with a wavelength of 525 nm appears as green light to the human eye. The energy of one photon of this

Sedbober [7]

Answer: The energy of one photon of the given light is $3.79\times 10^{-19}J$

Explanation:

To calculate the energy of one photon, we use Planck's equation, which is:

$E=\frac{hc}{\lambda}$

where,

$\lambda$ = wavelength of light = $525nm=5.25\times 10^{-7}m$ (Conversion factor: $1m=10^9nm$ )

h = Planck's constant = $6.625\times 10^{-34}J.s$

c = speed of light = $3\times 10^8m/s$

Putting values in above equation, we get:

$E=\frac{6.625\times 10^{-34}J.s\times 3\times 10^8m/s}{5.25\times 10^{-7}mm}\\\\E=3.79\times 10^{-19}J$

Hence, the energy of one photon of the given light is $3.79\times 10^{-19}J$

3 0

3 years ago