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Dominik [7]
2 years ago
7

a 5.00 L sample of helium expands to 12.0 L at which point the pressure is measured to be 0.720atm. what was the original pressu

re of the gas
Chemistry
1 answer:
stepan [7]2 years ago
5 0

Answer:

The answer to your question is  Pressure 1 = 1.73 atm

Explanation:

Data

Volume 1 = 5 l

Pressure 1 = ?

Volume 2 = 12 l

Pressure 2 = 0.72 atm

Process

To solve this problem use Boyle's law to solve this problem

                 Pressure 1 x Volume 1 = Pressure 2 x Volume 2

-Solve for Pressure 1

                 Pressure 1 = Pressure 2 x Volume 2 / Volume 1

-Substitutiion

                 Pressure 1 = 0.72 x 12 / 5

-Simplification

                Pressure 1 = 8.64/5

-Result

                 Pressure 1 = 1.73 atm

You might be interested in
Website
vredina [299]

Answer:

volume in L = 0.25 L

Explanation:

Given data:

Mass of Cu(NO₃)₂ = 2.43 g

Volume of KI = ?

Solution:

Balanced chemical equation:

2Cu(NO₃)₂  + 4KI    →    2CuI + I₂ + 4KNO₃

Moles of Cu(NO₃)₂:

Number of moles = mass/ molar mass

Number of moles = 2.43 g/ 187.56 g/mol

Number of moles = 0.013 mol

Now we will compare the moles of Cu(NO₃)₂ with KI.

                        Cu(NO₃)₂       :              KI    

                              2              :               4

                            0.013          :            4 × 0.013=0.052 mol

Volume of KI:

<em>Molarity = moles of solute / volume in L</em>

volume in L = moles of solute /Molarity

volume in L =  0.052 mol / 0.209 mol/L

volume in L = 0.25 L

6 0
2 years ago
A sample of fluorine gas is confined in a 5.0-L container at 0.432 atm and 37 °C. How many moles of gas are in this sample?
Ahat [919]

Answer:

About 0.08486 moles

Explanation:

PV=nRT, when P is the pressure in atmospheres, V is the volume in liters, n is the number of moles, R is the universal gas constant, and T is the temperature in Kelvin.

0.432 \cdot 5= n \cdot 0.0821 \cdot 310

n\approx 0.08486 moles

Hope this helps!

7 0
2 years ago
Pure platinum is too soft to be used in jewelry because it scratches easily. To increase the hardness so that it can be used in
Zina [86]

Answer:

percentage mass of platinum in the alloy ≈ 90.60 %

Explanation:

The alloy is 8.528 g sample of an alloy containing platinum and cobalt . The alloy react with excess nitric acid to form cobalt(ii) nitrate . Platinum is resistant to acid so it will definitely not react with the acid only the cobalt metal in the alloy will react with the acid.

The chemical reaction can be represented as follows:

Co (s) + HNO₃ (aq) → Co(NO₃)₂ (aq) +  NO₂ (l) + H₂O (l)

The balanced equation

Co (s) + 4HNO₃ (aq) → Co(NO₃)₂(aq) + 2NO₂ (l) + 2H₂O (l)

Cobalt is the limiting reactant

atomic mass of cobalt = 58.933 g/mol

Molar mass of Co(NO₃)₂ = 58.933 + 14 × 2 + 16 × 6 = 58.933 + 28 + 96 = 182.933  g

58.933 g of cobalt produce 182.933  g of  Co(NO₃)₂

? gram of cobalt will produce 2.49 g of Co(NO₃)₂

cross multiply

grams of cobalt that will react = (58.933 × 2.49)/182.933

grams of cobalt that will react = 146.74317000/182.933

grams of cobalt that will react= 0.8021689362 g

grams of cobalt that will react = 0.802 g

mass of platinum in the alloy  = 8.528 g - 0.802 g = 7.726 g

percentage  mass of platinum in the alloy = 7.726/8.528 × 100 = 772.600/8.528 = 90 .595 %

percentage mass of platinum in the alloy ≈ 90.60 %

6 0
2 years ago
Insoluble sulfide compounds are generally black in color. Which of the following combinations could yield a black precipitate? C
Lubov Fominskaja [6]

Answer:

Li₂S(aq) + Pb(NO₃)₂(aq)

2 K₂S(aq) + Sn(NO₃)₄(aq)

Explanation:

For these reactions, the products are:

1. Na₂S(aq) + 2 KCl(aq) → K₂S + 2 NaCl

2. Li₂S(aq) + Pb(NO₃)₂(aq) →  PbS + 2 Li(NO₃)

3. Pb(ClO₃)₂(aq) + 2 NaNO₃(aq) → Pb(NO₃)₂ + 2 Na(ClO₃)

4. AgNO₃(aq) + KCl(aq) → AgCl + KNO₃

5. 2 K₂S(aq) + Sn(NO₃)₄(aq) → SnS₂ + 4 KNO₃

K₂S is a soluble sulfide that, in solid state, is white. As K has a low electronegativity, the relative polar bond K-S allows its dissolution in water.

PbS is a black and insoluble compound. As Pb electronegativity is higher than K electronegativity, The bond is less-polar and its dissolution will not be allowed.

For the third reaction, all nitrates are soluble and Na(ClO₃) is also a very soluble compound.

AgCl is an insoluble white compound.

As Sn electronegativity is high, the solubility of this compound is very low. Also, this compound is black!

Thus, combinations could yield a black precipitate are:

Li₂S(aq) + Pb(NO₃)₂(aq)

2 K₂S(aq) + Sn(NO₃)₄(aq)

I hope it helps!

6 0
2 years ago
A 17.0-g sample of hf is dissolved in water to give 2.0 x 10 2 ml of solution. the concentration of the solution is:
fredd [130]
 The  concentration  of the solution  is   4.25 M

 Explanation

molarity=moles/volume in liters

moles  = mass/molar mass
molar mass  of HF = 19 + 1 =  20 g/mol
moles is therefore = 17.0 g/ 20 g/mol  = 0.85  moles

volume in  liters = 2  x10^2ml/1000 = 0.2  liters

therefore  molarity =  0.85/0.2 = 4.25  M
8 0
2 years ago
Read 2 more answers
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