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3 years ago

Identify a chemical reagent that can be used to distinguish solid CaCl2 from CaCO3

1 answer:

3 0

<span>The words you seek are soluble and insoluble.The chemical you want is an acid. Add an acid (acetic acid or hydrochloric acid) and the CaCO3 will fizz but CaCl2 will not</span>

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When NH3(g) reacts with N2O(g) to form N2(g) and H2O(g), 105 kcal of energy are evolved for each mole of NH3(g) that reacts. Wri

Ganezh [65]

Answer : The balanced chemical equation is,

$2NH_3(g)+3N_2O(g)\rightarrow 4N_2(g)+3H_2O(g)+210kcal$

Explanation :

Balanced chemical equation : It is defined as the number of atoms of individual elements present on the reactant side must be equal to the number of atoms of individual elements present on product side.

The given unbalanced chemical reaction is,

$NH_3(g)+N_2O(g)\rightarrow N_2(g)+H_2O(g)+105kcal$

This chemical reaction is an unbalanced reaction because in this reaction, the number of atoms of individual elements are not balanced.

In order to balanced the chemical reaction, the coefficient 2 is put before the $NH_3$ , the coefficient 3 is put before the $N_2O\text{ and }H_2O$ and the coefficient 4 is put before the $N_2$ .

The energy evolved in this reaction = $105Kcal\times 2=210Kcal$

Thus, the balanced chemical reaction will be,

$2NH_3(g)+3N_2O(g)\rightarrow 4N_2(g)+3H_2O(g)+210kcal$

7 0

3 years ago

Carbon-14 has a half-life of 5,700 years.

Maksim231197 [3]

Answer:

$3.106\ \text{g}$

Explanation:

$t_{1/2}$ = Half-life of carbon = 5700 years

t = Time at which the remaining mass is to be found = 10400 years

$m_0$ = Initial mass of carbon = 11 g

Decay constant is given by

$\lambda=\dfrac{\ln2}{t_{1/2}}$

Amount of mass remaining is given by

$m=m_0e^{-\lambda t}\\\Rightarrow m=m_0e^{-\dfrac{\ln2}{t_{1/2}} t}\\\Rightarrow m=11e^{-\dfrac{\ln 2}{5700}\times 10400}\\\Rightarrow m=3.106\ \text{g}$

The amount of the substance that remains after 10400 years is $3.106\ \text{g}$ .

5 0

3 years ago

What is the freezing point of a solution of 498mL of water (solute) dissolved in 2.50 L of ethanol (solvent), C2H5OH? The densit

jok3333 [9.3K]

Answer:

Freezing T° of solution is -142.4°C

Explanation:

This excersise is about colligative properties, in this case freezing point depression,

ΔT = Kf . m . i

Where ΔT = Freezing T° of solvent - Freezing T° of solution

Kf = Cryoscopic constant

m = mol/kg (molality)

i = Number of ions dissolved.

Water is not ionic, so i = 1

Let's find out m.

We determine mass of water, by density

498ml . 1 g/mL = 498 g

We convert the mass of water to moles → 498 g . 1mol/18g = 27.6 moles

We determine mass of solvent by density

2500 mL . 0.789 g/mL = 1972.5 g

Notice, we had to convert L to mL to cancel units.

1 cm³ = 1 mL

We convert the mass from g to kg → 1972.5 g . 1kg /1000g = 1.97kg

We determine m = mol/kg → 27.6mol / 1.97kg = 13.9 m

Kf for ethanol is: 1.99 °C/m

Freezing T° for ethanol is: -114.6°C

We replace at formula: - 114.6°C - Freezing T° solution = 1.99 °C/m . 13.9 m . 1

- 114.6°C - Freezing T° solution = 27.8 °C

- Freezing T° solution = 27.8°C + 114.6°C

Freezing T° Solution = - 142.4 °C

7 0

3 years ago

Why is the structure of a molecule important to its function

Scilla [17]

Answer:

It determines how biological molecules recognize and respond to one another with specificity.

Explanation:

A molecule has a characteristic size and shape. The precise shape of a molecule is usually very important to its function in the living cell. Molecular shape is crucial in biology because it determines how biological molecules recognize and respond to one another with specificity.

3 0

4 years ago

A sub-shell with n = 6, l = 2 can accommodate a maximum of:

Mrrafil [7]

Answer:

Explanation:

2n^2

n=6

2(6)^2=2×36

=72

8 0

3 years ago