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1 year ago

15

You are presented with a white solid and told that due to careless labeling it is not clear if the substance is barium chloride,

lead chloride, or zinc chloride.when you transfer the solid to a beaker and add water,the solid dissolves to give a clear solution.next a na2so4(aq) solution is added and a white precipitate forms. what is the identity of the unknown white solid?

1 answer:

Lady bird [3.3K]1 year ago

5 0

The given salts are Barium chloride, lead chloride and zinc chloride.

The balanced chemical reaction between barium chloride and sodium sulfate:

$BaCl_{2}(aq)+Na_{2}SO_{4}(aq)-->2NaCl(aq)+BaSO_{4}(s)_{white precipitate}$

The balanced chemical reaction between lead chloride and sodium sulfate:

$PbCl_{2}(aq)+Na_{2}SO_{4}(aq)-->2NaCl(aq)+PbSO_{4}(s)_{white precipitate}$

The balanced chemical reaction between zinc chloride and sodium sulfate:

$ZnCl_{2}(aq)+Na_{2}SO_{4}(aq)-->2NaCl(aq)+ZnSO_{4}(aq)$

Both Barium chloride and lead chloride produce a white precipitate of their respective sulfates upon reaction with sodium sulfate. But BaCl2 is readily soluble in water where as Lead chloride is insoluble in water.

Therefore, the compound is barium chloride.

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Among the alkali metals, the tendency to react with other substances. A. does not vary among the members of the group. . B. incr

yKpoI14uk [10]

B is correct. As you move down group 1, the elements become more reactive with other elements because the electrons have a weaker attraction to their own atoms nucleus which means attraction with other elements is much stronger, making the atom more reactive.

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1 year ago

A 0.380 kg sample of aluminum (with a specific heat of 910.0 J/(kg x K)) is heated to 378 K and then placed in 2.40 kg of water

lbvjy [14]

Answer:

The equilibrium temperature of the system is 276.494 Kelvin.

Explanation:

Let consider the system formed by the sample of aluminium and water as a control mass, in which the sample is cooled and water is heated until thermal equilibrium is reached. The energy process is represented by First Law of Thermodynamics:

$Q_{water} -Q_{sample} = 0$

$Q_{water} = Q_{sample}$

Where:

$Q_{water}$ - Heat received by water, measured in joules.

$Q_{sample}$ - Heat released by the sample of aluminium, measured in joules.

Given that no mass is evaporated, the previous expression is expanded to:

$m_{w}\cdot c_{p,w}\cdot (T-T_{w}) = m_{s}\cdot c_{p,s}\cdot (T_{s}-T)$

Where:

$m_{s}$ , $m_{w}$ - Mass of water and the sample of aluminium, measured in kilograms.

$c_{p,s}$ , $c_{p,w}$ - Specific heats of the sample of aluminium and water, measured in joules per kilogram-Kelvin.

$T_{s}$ , $T_{w}$ - Initial temperatures of the sample of aluminium and water, measured in Kelvin.

$T$ - Temperature which system reaches thermal equilibrium, measured in Kelvin.

The final temperature is now cleared:

$(m_{w}\cdot c_{p,w}+m_{s}\cdot c_{p,s})\cdot T = m_{s}\cdot c_{p,s}\cdot T_{s}+m_{w}\cdot c_{p,w}\cdot T_{w}$

$T = \frac{m_{s}\cdot c_{p,s}\cdot T_{s}+m_{w}\cdot c_{p,w}\cdot T_{w}}{m_{w}\cdot c_{p,w}+m_{s}\cdot c_{p,s}}$

Given that $m_{s} = 0.380\,kg$ , $m_{w} = 2.40\,kg$ , $c_{p,s} = 910\,\frac{J}{kg\cdot K}$ , $c_{p,w} = 4186\,\frac{J}{kg\cdot K}$ , $T_{s} = 378\,K$ and $T_{w} = 273\,K$ , the final temperature of the system is:

$T = \frac{(0.380\,kg)\cdot \left(910\,\frac{J}{kg\cdot K} \right)\cdot (378\,K)+(2.40\,kg)\cdot \left(4186\,\frac{J}{kg\cdot K} \right)\cdot (273\,K)}{(2.40\,kg)\cdot \left(4186\,\frac{J}{kg\cdot K} \right)+(0.380\,kg)\cdot \left(910\,\frac{J}{kg\cdot K} \right)}$

$T = 276.494\,K$

The equilibrium temperature of the system is 276.494 Kelvin.

7 0

2 years ago

Neutrons were discovered in 1932, more than 10 years after the existence of isotopes was confirmed. What property of electrons a

kirza4 [7]

Protons and neutrons are the sub-atomic particles present in the nucleus of an atom where as electrons are present revolving round the nucleus in orbits. Electrons are negatively charged, protons are positively charged where as a neutron is a neutral species. It is the presence of electric charge that lead to the discovery of electrons (negative charge) and protons (positive charge), while it took time to discover neutral as they were electrically neutral species. Neutrons carrying no charge were not detected easily by passing electromagnetic radiations. Therefore, neutrons were the last of the three subatomic particles, to be discovered.

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2 years ago

A scientist is wondering why a certain region in the ocean doesn't have maximum phytoplankton growth, despite having plenty of n

Advocard [28]

Answer:

C The water had adequate nitrogen and phosphorus, so it is likely iron limited.

Explanation:

Phytoplankton are single- cell organisms that live in oceans.

They require nitrogen, phosphorus and trace amount of iron to survive.

From the scientist's results after testing the water for nitrogen and phosphorus,there are reasonable amount of these elements.

Therefore insufficient iron in the water is the reason why he could find plenty phytoplankton in the ocean.

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2 years ago

This is the chemical formula for nickel tetracarbonyl (a powerfully poisonous liquid used in nickel refining) Ni(CO)4 A chemical

OverLord2011 [107]

Answer : The number of moles of oxygen present in a sample are 11.3 moles.

Explanation :

The given compound is, $Ni(CO)_4$

By the stoichiometry we can say that, 1 mole of of $Ni(CO)_4$ has 4 moles of CO.

Or we can say that, 1 mole of of $Ni(CO)_4$ has 1 mole of nickel (Ni), 4 moles of carbon (C) and 4 moles of oxygen.

That means,

Number of moles of carbon = Number of moles of oxygen

As we are given that:

Number of moles of carbon = 11.3 moles

So, number of moles of oxygen = number of moles of carbon = 11.3 moles

Therefore, the number of moles of oxygen present in a sample are 11.3 moles.

7 0

2 years ago