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3 years ago

Hannah added a silvery white metal to a beaker of cold water and noticed that

Chemistry

1 answer:

Schach [20]3 years ago

3 0

Answer:

A. Hot water increases the collision rate of the molecules, causing the

reaction to occur faster.

Explanation:

Hot water molecules move faster than cold water molecules.

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Some instruments differentiate individual quanta of electromagnetic radiation based on their energies. assume such an instrument

bulgar [2K]

Answer:

5.68×10¯¹⁰ m

Explanation:

From the question given above, the following data were obtained:

Energy (E) = 3.50×10¯¹⁶ J

Wavelength (λ) =?

Energy (E) and wavelength (λ) are related according to the following formula:

E = hv/λ

Where

E => is the energy

h => is the Planck's constant

v => is the velocity of electromagnetic radiation

λ => is the wavelength of the radiation.

With the above formula, we can obtain the wavelength of the radiation as follow:

Energy (E) = 3.50×10¯¹⁶ J

Planck's constant (h) = 6.63×10¯³⁴ Js

Velocity (v) = 3×10⁸ m/s

Wavelength (λ) =?

E = hv/λ

3.50×10¯¹⁶ = 6.63×10¯³⁴ × 3×10⁸ / λ

3.50×10¯¹⁶ = 1.989×10¯²⁵/ λ

Cross multiply

3.50×10¯¹⁶ × λ = 1.989×10¯²⁵

Divide both side by 3.50×10¯¹⁶

λ = 1.989×10¯²⁵ / 3.50×10¯¹⁶

λ = 5.68×10¯¹⁰ m

Thus, the wavelength of the radiation is

5.68×10¯¹⁰ m

7 0

3 years ago

Calculate pressure (at STP) in 10.0 L vessel after reaction of 1.0 L hydrochloric acid (concentration 35 % and density 1.28 g/cu

SCORPION-xisa [38]

Answer:

The pressure in the vessel is 13,3 atm.

Explanation:

2 HCl (aq)+ CaCO₃ (s) → CaCl₂(aq)+ H₂O(l)+ CO₂(g)

The increase in the pressure of the vessel after the reaction is by formation of a gas (CO₂). So we have to find the produced moles of this gas and apply the gas ideal law to find the pressure.

We have to find the limit reactant, to do so, we have to calculate the moles of each reactant in the reaction, the one that have the less moles will be the limit reactant:

HCl:

1,0L × (35/100) × (1000 cm³/1L) × (1,28 g/ 1cm³) × (1mol HCl/ 36,46 g) ÷ 2mol

<em>(Concentration) (L to cm³) (cm³ to g) (g to mol) (moles of reaction)</em>

moles of HCl= 6,14 mol

CaCo₃:

1,0 kg × (96/100) × (1000 g/1kg) × (1 mol/100,09g)

<em>(Limestone) (CaCo₃ in limestone) (kg to g) (g to mol) </em>

moles of CaCo₃= 9,59 mol

So, reactant limit is HCl

This reaction have a yield of 97%. So, the CO₂ moles are:

6,14 mol × 97÷ = 5,96 mol CO₂

The ideal gas formula to obtain pressure is:

P = nRT/V

Where: n = 5,96mol; R= 0,082 atm×L/mol×K; T = 273,15 (until STP conditions) and V= 10,0 L

Replacing this values in the equation the pressure is

P = 13,3 atm

I hope it helps!

7 0

3 years ago

A compound is found to contain 30.45 % nitrogen and 69.55 % oxygen by mass. To answer the question, enter the elements in the or

butalik [34]

Answer: The molecular formula of the compound is $NO_2$

Explanation:

Converting all these percentages into mass.

We take the total mass of the compound to be 100 grams, so, the percentages given for each element becomes its mass.So, the mass of each element is equal to the percentage given.

Mass of N = 30.45 g

Mass of O = 69.55 g

Step 1 : convert given masses into moles.

Moles of N= $\frac{\text{ given mass of N}}{\text{ molar mass of N}}= \frac{30.45g}{14g/mole}=2.175moles$

Moles of O = $\frac{\text{ given mass of O}}{\text{ molar mass of O}}= \frac{69.55g}{16g/mole}=4.347moles$

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

For N = $\frac{2.175}{2.175}=1$

For O = $\frac{4.347}{2.175}=2$

The ratio of N: O = 1: 2

Hence the empirical formula is $NO_2$ .

Empirical mass of $NO_2$ is = 14(1)+16 (2)=46

The equation used to calculate the valency is:

$n=\frac{\text{molecular mass}}{\text{empirical mass}}=\frac{46.01}{46}=1$

Step 3: To calculate the molecular formula= $n\times {\text {Equivalent Formula}}=1\times NO_2=NO_2$

Hence, the molecular formula of the compound is $NO_2$

5 0

4 years ago

What is the ph of a 0.20 M solution of NH4Cl? [Kb(NH3) = 1.8 x 10^-5]

Pavlova-9 [17]

"NH4+ <----> NH3 + H+

The constant of this equilibrium is: K = Kw / Kb = 1 x 10^-14 / 1.8 x 10^-5 =5.56 x 10^-10

5.56 x 10^-10 = x^2 / 0.20-x

x = [H+] =1.1 x 10^-5 M

pH = 5.0"

8 0

3 years ago

Read 2 more answers

What is a mole?

leva [86]

It's hard to relate a mole to carbon or sulfur. Imagine if I walked up to you and said, "What's the relation between a dozen and donuts?"

A mole is a form of measurement for atoms, more specifically, 6.02 * 10^23 atoms. I suppose you could relate it to Carbon or Sulfur, since the number of atoms of each are usually measured in moles.

Carbon and Sulfur don't have a set number of moles (Just like donuts don't have to be a dozen), so it's hard to answer your second question.
In the atomic table, the number you see under the element is the molar mass, which is the weight of an a mole of the element. In this way, I guess there's a mole of Carbon and Sulfur present, if we're looking at the periodic table.

-T.B.

8 0

3 years ago