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3 years ago

Give the number of protons, neutrons and electrons in 99Tc

Chemistry

1 answer:

miss Akunina [59]3 years ago

5 0

Explanation:

Tc - 99 is technetium 99.

It is a radioactive element that decays spontaneously. It has a half-life of 211,000 years and decays to stable ruthenium.

On the periodic table, it has an atomic number of 43;

Mass number = 99

Atomic number = number of protons = number of electrons in atom

Number of protons in Tc is 43

electron is 43

Mass number = number of protons + number of neutrons

Number of neutrons = mass number - number of protons = 99-43 = 56

learn more:

Atomic number brainly.com/question/2057656

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EL hidroxido de sodio reacciona con el sulfato de hierro (II) para formar sulfato de sdio e hidroxido ferroso. Si se hace reacci

Oduvanchick [21]

Answer:

280.8 g

Explanation:

Definimos la reaccion:

2NaOH + FeSO₄ → Na₂SO₄ + Fe(OH)₂

Como tenemos la masa de NaOH, asumimos que el sulfato de hierro (II) es el reactivo en exceso.

Definimos masa de reactivo: 250 g . 1mol / 40g = 6.25 mol

2 moles de NaOH producen 1 mol de hidroxido ferroso

Entonces 6.25 moles producirán, la mitad (6.25 . 1) /2 = 3.125 moles

Convertimos los moles a masa:

3.125 mol . 89.85 g/mol = 280.8 g

7 0

2 years ago

6. Which group of compounds is described as insoluble?

Sedaia [141]

Answer:phosphates are insoluble in water

Explanation:

3 0

3 years ago

CO2(g)+CCl4(g)⇌2COCl2(g) Calculate ΔG for this reaction at 25 ∘C under these conditions: PCO2PCCl4PCOCl2===0.140 atm0.185 atm0.7

padilas [110]

<u>Answer:</u> The $\Delta G$ for the reaction is 54.425 kJ/mol

<u>Explanation:</u>

For the given balanced chemical equation:

$CO_2(g)+CCl_4(g)\rightleftharpoons 2COCl_2(g)$

We are given:

$\Delta G^o_f_{CO_2}=-394.4kJ/mol\\\Delta G^o_f_{CCl_4}=-62.3kJ/mol\\\Delta G^o_f_{COCl_2}=-204.9kJ/mol$

To calculate $\Delta G^o_{rxn}$ for the reaction, we use the equation:

$\Delta G^o_{rxn}=\sum [n\times \Delta G_f(product)]-\sum [n\times \Delta G_f(reactant)]$

For the given equation:

$\Delta G^o_{rxn}=[(2\times \Delta G^o_f_{(COCl_2)})]-[(1\times \Delta G^o_f_{(CO_2)})+(1\times \Delta G^o_f_{(CCl_4)})]$

Putting values in above equation, we get:

$\Delta G^o_{rxn}=[(2\times (-204.9))-((1\times (-394.4))+(1\times (-62.3)))]\\\Delta G^o_{rxn}=46.9kJ=46900J$

Conversion factor used = 1 kJ = 1000 J

The expression of $K_p$ for the given reaction:

$K_p=\frac{(p_{COCl_2})^2}{p_{CO_2}\times p_{CCl_4}}$

We are given:

$p_{COCl_2}=0.735atm\\p_{CO_2}=0.140atm\\p_{CCl_4}=0.185atm$

Putting values in above equation, we get:

$K_p=\frac{(0.735)^2}{0.410\times 0.185}\\\\K_p=20.85$

To calculate the gibbs free energy of the reaction, we use the equation:

$\Delta G=\Delta G^o+RT\ln K_p$

where,

$\Delta G$ = Gibbs' free energy of the reaction = ?

$\Delta G^o$ = Standard gibbs' free energy change of the reaction = 46900 J

R = Gas constant = $8.314J/K mol$

T = Temperature = $25^oC=[25+273]K=298K$

$K_p$ = equilibrium constant in terms of partial pressure = 20.85

Putting values in above equation, we get:

$\Delta G=46900J+(8.314J/K.mol\times 298K\times \ln(20.85))\\\\\Delta G=54425.26J/mol=54.425kJ/mol$

Hence, the $\Delta G$ for the reaction is 54.425 kJ/mol

7 0

3 years ago

Negatively charged Adam or group of Adams is called a(n)

bija089 [108]

Answer:

Anion

Explanation:

Anion is an atom or group of atoms that are negatively charged.

Cations are positively charged

Anode is a positively charged pole that conducts electricity (remember electrolysis)

Cathode is a negatively charged pole that conducts electricity (remember electrolysis too)

3 0

3 years ago

Which theory describes the motion of and force driving earth’s plates?

swat32

The theory that describes the motion and force driving earth's plates is Plate tectonics

Explanation:

Plate tectonics states that the outer shell of the Earth is divided into plates that glide and move over the mantle which is the surface of the earth.

The mantle is the rocky inner layer above the core of the Earth.

Plate tectonics helped the geologists to explain how continents could move around the planet.

There are 9 major plate tectonics , namely North American, Pacific, Eurasian, Australian, African, Indo - Australian,Indian South American and Antarctic. These plates have been named after the land form found on them.

7 0

2 years ago