A gas occupies 72.1 L at STP. At what temperature Kelvin would the gas occupy 85.9 L at a pressure of 93.6 kPa?

A solution contains some or all of the ions Cu²⁺, Al³⁺, K⁺, Ca²⁺, Ba²⁺, Pb²⁺, and NH₄⁺. The following tests were performed, in o

Nina [5.8K]

Answer:

Among given, the ions which are present in the given solution are:

Cu²⁺, Al³⁺ and K⁺

Among given, the ions which are absent in the given solution are:

Pb²⁺, Ca²⁺ and Ba²⁺

The ion which no conclusion is NH₄⁺.

Explanation:

Reagents given are used in salt analysis. The salt analysis is a qualitative analysis used for the identification of cations and anions of inorganic salts.

HCl is used for the identification of group I cations. As no reaction occurred when HCl is added to the solution, that means group I cations are absent.

So, among the given Pb²⁺ is a group I cation, therefore, Pb²⁺ is absent.

H₂S along with HCl is used for the identification group II salts.

Addition of Addition of H₂S with 0.2 M HCl produced a black solid, so, group II cation Cu²⁺ is present.

H₂S is used for the identification of group III cations.

When H₂S is added to the filtrate of group II, white precipitate is formed that means group III cations are present. Among group III cations, Al³⁺ is present.

Addition of (NH₄)₂HPO₄ in the presence of NH₃ is used for the identification of group IV cations.

As no precipitate is formed, therefore, group IV cations are absent.

So among given options, Ca²⁺ and Ba²⁺ are absent in the given solution.

The final supernatant when heated produces purple flame which indicates the presence of K⁺.

Therefore, among given, the ions which are present in the given solution are:

Cu²⁺, Al³⁺ and K⁺

Among given, the ions which are absent in the given solution are:

Pb²⁺, Ca²⁺ and Ba²⁺

The ion which no conclusion is NH₄⁺.

5 0

3 years ago

If the temperature remains constant, an increase in pressure will

Svetradugi [14.3K]

Have a decrease in volume.

6 0

3 years ago

Read 2 more answers

A chemist prepares a sample of helium gas at a certain pressure, temperature and volume and then removes all but a fourth of the

cupoosta [38]

Answer:

The temperature must be changed to 4 times of the initial temperature so as to keep the pressure and the volume the same.

Explanation:

Pressure in the container is P and volume is V.

Temperature of the helium gas molecules = $T_1$

Molecules helium gas = x

Moles of helium has = $n_1= \frac{x}{N_A}$

PV = nRT (Ideal gas equation)

$PV=n_1RT_1$ ...[1]

After removal of helium gas only a fourth of the gas molecules remains and pressure in the container and volume should remain same.

Molecules of helium left after removal = $\frac{x}{4}$

Moles of helium has left after removal = $n_2= \frac{x}{4\times N_A}$

$PV=n_2RT_2$ ...[2]

$n_1RT_1=n_2RT_2$

$\frac{x}{N_A}\times T_1=\frac{x}{4\times N_A}\times T_2$

$T_1=\frac{T_2}{4}$

$T_2=4T_1$

The temperature must be changed to 4 times of the initial temperature so as to keep the pressure and the volume the same.

6 0

4 years ago

How many molecules are in 3 moles of potassium bromide (KBr)

sattari [20]

Answer:

Your strategy here will be to use the molar mass of potassium bromide,

KBr

, as a conversion factor to help you find the mass of three moles of this compound.

So, a compound's molar mass essentially tells you the mass of one mole of said compound. Now, let's assume that you only have a periodic table to work with here.

Potassium bromide is an ionic compound that is made up of potassium cations,

K

+

, and bromide anions,

Br

−

. Essentially, one formula unit of potassium bromide contains a potassium atom and a bromine atom.

Use the periodic table to find the molar masses of these two elements. You will find

For K:

M

=

39.0963 g mol

−

1

For Br:

M

=

79.904 g mol

−

1

To get the molar mass of one formula unit of potassium bromide, add the molar masses of the two elements

M

M KBr

=

39.0963 g mol

−

1

+

79.904 g mol

−

1

≈

119 g mol

−

So, if one mole of potassium bromide has a mas of

119 g

m it follows that three moles will have a mass of

3

moles KBr

⋅

molar mass of KBr



119 g

1

mole KBr

=

357 g

You should round this off to one sig fig, since that is how many sig figs you have for the number of moles of potassium bromide, but I'll leave it rounded to two sig figs

mass of 3 moles of KBr

=

∣

¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯

a

360 g

a

∣

−−−−−−−−−

Explanation:

answer: 360 g 

6 0

3 years ago

WHICH OF THE GENOTYPES IN NUMBER 1 WOULD BE CONSIDERED PUREBRED

Rasek [7]

Purebred — Also called HOMOZYGOUS and consists of gene pairs with genes that are the SAME. Hybrid - Also called HETEROZYGOUS and consists of gene pairs that are D i'FFEREN'i". Genotype is the actual GENE makeup represented by LE'H'ERS.

3 0

3 years ago