What is the boiling point of gold?

If someone takes a material that looks pure, and then they do something to it that results

Sati [7]

Answer:

The determination of the nature of the combination of the two separate materials in the original material that looks pure is based on the characteristic of the change process they undergo to become two separate materials.

Therefore, they can know if they initially had a mixture or a compound by the following steps;

1) If the two separated materials can be easily remixed to form the original material, then they likely have a mixture of the two separate materials

2) If the process that results in the formation of the two separate materials, involves the absorption or evolves heat or other forms of energy, then the original substance was a compound

3) If the two newly formed materials is seen to be a permanent change, then the original material was a compound

Explanation:

7 0

2 years ago

How many electrons would be in a calcium cation with a positive 2 charge?

kondor19780726 [428]

Number of electrons in a Ca²⁺ = 18

<h3>Further explanation </h3>

In an atom there are levels of energy in the shell and sub shell

This energy level is expressed in the form of electron configurations.

Writing electron configurations starts from the lowest to the highest sub-shell energy level. There are 4 sub-shells in the shell of an atom, namely s, p, d and f. The maximum number of electrons for each sub shell is

• s: 2 electrons

• p: 6 electrons

• d: 10 electrons and

• f: 14 electrons

Charging electrons in the sub shell uses the following sequence:

The element Ca has an atomic number of 20, so the number of electrons and protons (in neutral atoms) is also 20

Electron configuration of Ca : <em>1s², 2s², 2p⁶, 3s², 3p⁶, 4s² ⇒[Ar] 4s²</em>

When Ca releases 2 electrons to gain stability (forming Ca²⁺ cations), the number of electrons becomes:

$\tt 20-2 = 18$

and the electron configuration (Ca²⁺ ) becomes:

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6 0

2 years ago

Which statements describe the death of stars? Check all that apply.

Sveta_85 [38]

Answer:A and B

Explanation:a stats final stages of life depend on its mass and stars die when they run out of fuel

5 0

3 years ago

Read 2 more answers

Hydrogen sulfide gas is combusted with oxygen gas to produce sulfur dioxide gas and water vapour. If there is 48.4 L of oxygen a

Kitty [74]

Answer:

2H2S + 3O2 → 2SO2 + 2H2O

V(O2) = 48.4 L

p = 105 kPa = 1.036 atm

T = 190 + 273 = 463 K

Ideal gas law:

pV = nRT

n = \frac{pV}{RT}n=

RT

pV

R = 0.08206 L×atm/mol×K

n(O2) = \frac{1.036 \times 48.4}{0.08206 \times 463}=1.319 \; mol=

0.08206×463

1.036×48.4

=1.319mol

According to the reaction:

n(H2S) = \frac{2}{3}

3

2

n(O2) = \frac{2}{3} \times 1.319 = 0.8798 \;mol

3

2

×1.319=0.8798mol

V = \frac{nRT}{p} \\ V(H_2S) = \frac{0.8798 \times 0.08206 \times 463}{1.036}=32.26 \;LV=

p

nRT

V(H

2

S)=

1.036

0.8798×0.08206×463

=32.26L

Answer: 32.26 L

Explanation:

5 0

3 years ago

I need help on both a and b of question 1

marishachu [46]

Answer:

(a) -0.00017 M/s;

(b) 0.00034 M/s

Explanation:

(a) Rate of a reaction is defined as change in molarity in a unit time, that is:

$r = \frac{\Delta c}{\Delta t}$

Given the following reaction:

$2 N_2O_5 (g)\rightleftharpoons 4 NO_2 (g) + O_2 (g)$

We may write the rate expression in terms of reactants firstly. Since reactants are decreasing in molarity, we're adding a negative sign. Similarly, if we wish to look at the overall reaction rate, we need to divide by stoichiometric coefficients:

$r = -\frac{\Delta [N_2O_5]}{2 \Delta t}$