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Ronch [10]
2 years ago
11

Mendeleev placed thallium (Tl) in the same group as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs). Ho

wever, the modern periodic table doesn’t place thallium in this group. Use the periodic table to find the properties of thallium. Explain why Mendeleev might have grouped thallium in the same group as lithium and sodium. Also explain how thallium is different from the other five elements.
Chemistry
1 answer:
IceJOKER [234]2 years ago
4 0

Answer:

Mendeleev placed thallium (Tl) in the same group as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs)

Explanation:

Properties of Thallium :

Thallium is a heavy metal denoted by symbol Tl. It is placed in 13th group and 6th period of modern periodic table. It is very soft in nature. It has 3 valency. It does not occur freely in environment.

Mendeleev  grouped thallium in the same group as lithium and sodium because of he found that as Li, Na etc. have compound with one atom of chlorine(Cl), Thallium(Tl) also forms TlCl. Therefore he placed Tl with these elements.

Thallium is different from the other five elements

Tl has 3 valency whereas lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs) has only 1 valency.

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How many possible stereoisomers are there of propylene glycol, an organic compound found in clearasil acne cream, caladryl, colg
vova2212 [387]

Answer:

2

Explanation:

Isomers are molecules with the same molecular formula, but with some difference. If that difference is in the manner the atoms are distributed in the molecule, they are called structural isomers; if the difference is the way the molecule is in space, they're called space isomers (cis/trans); and there are the stereoisomers, which the molecules are images that can be overlapping.

The stereoisomers have the property to deviate the polarized light, and, when a molecule has a chiral carbon, it means that it has stereoisomers. The number of stereoisomers is 2ⁿ, where n is the number of chiral carbons.

Chiral carbon is a carbon that bonds with four different structures. So, below is represented the molecule of propylene glycol, and it has only one chiral carbon (see the blue arrow), so, it has only 2 stereoisomers.

6 0
2 years ago
A sample of cacl2⋅2h2o/k2c2o4⋅h2o solid salt mixture is dissolved in ~150 ml de-ionized h2o. the oven dried precipitate has a ma
Paraphin [41]

We are given that the balanced chemical reaction is:

cacl2⋅2h2o(aq) + k2c2o4⋅h2o(aq) ---> cac2o4⋅h2o(s) + 2kcl(aq) + 2h2o(l)

We known that the product was oven dried, therefore the mass of 0.333 g pertains only to that of the substance cac2o4⋅h2o(s). So what we will do first is to convert this into moles by dividing the mass with the molar mass. The molar mass of cac2o4⋅h2o(s) is molar mass of cac2o4 plus the molar mass of h2o.

molar mass cac2o4⋅h2o(s) = 128.10 + 18 = 146.10 g /mole

moles cac2o4⋅h2o(s) = 0.333 / 146.10 = 2.28 x 10^-3 moles

Looking at the balanced chemical reaction, the ratio of cac2o4⋅h2o(s) and k2c2o4⋅h2o(aq) is 1:1, therefore:

moles k2c2o4⋅h2o(aq) = 2.28 x 10^-3 moles

Converting this to mass:

mass k2c2o4⋅h2o(aq) = 2.28 x 10^-3 moles (184.24 g /mol) = 0.419931006 g

 

Therefore:

The mass of k2c2o4⋅<span>h2o(aq) in the salt mixture is about 0.420 g</span>

3 0
2 years ago
Read 2 more answers
At 800 K, the equilibrium constant, Kp, for the following reaction is 3.2 × 10–7. 2 H2S(g) ⇌ 2 H2(g) + S2(g) A reaction vessel a
djverab [1.8K]

Answer:

0.008945 atm

Explanation:

In the reaction:

2H2S(g) ⇌ 2 H2(g) + S2(g)

Kp is defined as:

Kp = P_{H_{2}}^2P_{S_{2}} / P_{H_{2}S}^2

<em>Where P is the pressure of each compound in equilibrium.</em>

If initial pressure of H2S is 3.00atm, concentrations in equilibrium are:

H2S = 3.00 atm - 2X

H2 = 2X

S2: = X

Replacing:

3.2x10^{-7} = (2X)^2X / (3-2X)^2

3.2x10^{-7} = 4X^3 / 9- 6X+4X^2

0 = 4X³ - 1.28x10⁻⁶X² + 1.92x10⁻⁶X - 2.88x10⁻⁶

Solving for X:

X = 0.008945 atm

As in equilibrium, pressure of S2 is X, <em>pressure is 0.008945 atm</em>

7 0
2 years ago
What is the change in enthalpy in kilojoules when 3.24 g of CH3OH is completely reacted according to the following reaction 2 CH
vodka [1.7K]

Answer:

12.78 kJ

Explanation:

The correct balanced reaction would be

2CH_3OH\rightarrow 2CH_4+O_2\Delta H=252.8\ \text{kJ}

Mass of methanol = 3.24\ \text{g}

Moles of methanol can be obtained by dividing the mass of methanol with its molar mass (32.04\ \text{g/mol})

\dfrac{3.24}{32.04}=0.10112\ \text{moles}

Enthalpy change for the number of moles is given by

\dfrac{\text{Number of moles of methanol in the reaction}}{\text{Enthalpy change in the reaction}}=\dfrac{\text{Number of moles in 3.24 g of methanol}}{\text{Enthaply in change in the mass of methanol}}

\\\Rightarrow\dfrac{2}{252.8}=\dfrac{0.10112}{\Delta H}\\\Rightarrow \Delta H=\dfrac{0.10112\times 252.8}{2}\\\Rightarrow \Delta H=12.781568\approx 12.78\ \text{kJ}

The change in enthalpy is 12.78 kJ.

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2 years ago
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weqwewe [10]
Less friction to stop the wheel from turning
8 0
2 years ago
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