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3 years ago

Which of these four elements is the most reactive metal?

Chemistry

2 answers:

Ksivusya [100]3 years ago

5 0

Answer:

Sodium (NA)

Explanation:

suter [353]3 years ago

5 0

Answer:

rubidium: rb

Explanation:

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How many are molecules ( or formula) in each sample?

andre [41]

Answer:

$4.010 \times 10^{25} \text { molecules of } \mathrm{NaHCO}_{3} \text { present in } 55.93 \mathrm{kg} \text { of } \mathrm{NaHCO}_{3}$
$16.86 \times 10^{26} \text { molecules of } \mathrm{Na}_{3} \mathrm{PO}_{4} \text { present in } 459 \mathrm{kg}\left(4.59 \times 10^{5} \mathrm{gm}\right) \text { of } \mathrm{Na}_{3} \mathrm{PO}_{4}$

Explanation:

Number of molecules for $55.93 \mathrm{kg} \text { of } \mathrm{NaHCO}_{3}$

$\text { Firstly molar mass is calculated of } \mathrm{NaHCO}_{3}:$

Atomic mass of Na + H + C + 3(O) = 22.99 + 1.008 + 12.01 + 3 × 16.00 = 84.00 g/mol

$\text { Number of molecules of } \mathrm{NaHCO}_{3} \text { in } 55.93 \text { kg are as follows: }$

$55.93 \times\left(10^{3} \mathrm{gm}\right) \times \frac{1 \mathrm{mol} \mathrm{NaHCO}_{3}}{84.00 \mathrm{gm} \mathrm{NaHCO}_{3}} \times\left(6.022 \times 10^{23} \mathrm{molecules} \text { i.e Avogadro number }\right)$

$=4.010 \times 10^{26} \text { molecules of } \mathrm{NaHCO}_{3} \text { present in } 55.93 \mathrm{kg} \text { of } \mathrm{NaHCO}_{3}$

Number of molecules for for $\left(4.59 \times 10^{5} \mathrm{gm}\right) \text { of } \mathrm{Na}_{3} \mathrm{PO}_{4}$

$\text { Firstly molar mass is calculated of } \mathrm{Na}_{3} \mathrm{PO}_{4}$

= Atomic mass of 3(Na) + P + 4(O)

= 3(22.99) + 30.97 + 4(16.00) = 163.94 g/mol

$459 \times\left(10^{3} \mathrm{gm}\right) \times \frac{1 \mathrm{mol} N a_{3} P O_{4}}{163.94 \mathrm{gm} N a_{3} P O_{4}} \times\left(6.022 \times 10^{23} \mathrm{molecules} \text { i.e Avogadro number) } / 1 \mathrm{mol}\right.$

$=16.86 \times 10^{26} \text { molecules of } \mathrm{Na}_{3} \mathrm{PO}_{4} \text { present in } 459 \mathrm{kg}\left(4.59 \times 10^{5} \mathrm{gm}\right) \text { of } \mathrm{Na}_{3} \mathrm{PO}_{4}$

8 0

3 years ago

Many hospitals, and some doctors\' offices, use radioisotopes for diagnosis and treatment, or in palliative care (relief of symp

Phantasy [73]

Answer:

a) $^{131}_{53} I$

b) $^{192}_{77} Ir$

c) $^{153}_{62} Sm$

Explanation:

The symbols of the isotopes are written like

$^{A}_{Z} X$

where,

X is the element

A is the mass number (protons + neutrons)

Z is the atomic number (protons)

a) Iodine-131

The atomic number of iodine is 53. The mass number of this isotope is 131. The symbol is $^{131}_{53} I$ .

b) Iridium-192

The atomic number of iridium is 77. The mass number of this isotope is 192. The symbol is $^{192}_{77} Ir$ .

c) Samarium-153

The atomic number of samarium is 62. The mass number of this isotope is 153. The symbol is $^{153}_{62} Sm$ .

8 0

2 years ago

A reaction has a forward rate constant of 2.3 × 106 s-1 and an equilibrium constant of 4.0 × 108. what is the rate constant for

avanturin [10]

Answer is: 5,75·10⁻¹.
Kf = 2,3·10⁶ 1/s.
K = 4,0·10⁸ 1/s.
Kr = ?
Kf - forward rate constant.
K - equilibrium constant.
Kr - reverse rate constant.
Since both Kf and Kr are constants at a given temperature, their ratio is also a constant that is equal to the equilibrium constant K.
K = Kf/Kr.
Kr = Kf/K = 2,3·10⁶ 1/s ÷ 4,0·10⁸ 1/s = 5,75·10⁻¹.

5 0

2 years ago

26. Balance the following equations: Ca(s) + H3PO4(aq)Ca3(PO4)2(s) + H2(g)

yKpoI14uk [10]

Hey there!

Ca + H₃PO₄ → Ca₃(PO₄)₂ + H₂

Balance PO₄.

1 on the left, 2 on the right. Add a coefficient of 2 in front of H₃PO₄.

Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + H₂

Balance H.

6 on the left, 2 on the right. Add a coefficient of 3 in front of H₂.

Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂

Balance Ca.

1 on the right, 3 on the right. Add a coefficient of 3 in front of Ca.

3Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂

Our final balanced equation:

3Ca + 2H₃PO₄ → Ca₃(PO₄)₂ + 3H₂

Hope this helps!

3 0

3 years ago

Lab activity - Law of Conservation of Mass with vinegar and baking soda.

lesya [120]

Answer: I BIG DUMB

Explanation:

7 0

2 years ago

Which of these four elements is the most reactive metal?​

Which of these four elements is the most reactive metal?