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3 years ago

Precipitation reactions always occur when two aqueous solutions are mixed (T/F)

Chemistry

1 answer:

Studentka2010 [4]3 years ago

7 0

Answer: The given statement is false.

Explanation:

Precipitation reaction is defined as the chemical reaction in which two aqueous solution upon mixing together results in the formation of an insoluble solid.

For example, $NaCl(aq) + AgNO_{3} \rightarrow NaNO_{3}(aq) + AgCl(s)$

Here AgCl is present in solid state so, it is the precipitate.

But it is not necessarily true that two aqueous solutions will always result in the formation of a precipitate.

For example, $NaCl(aq) + KNO_{3}(aq) \rightarrow KCl(aq) + NaNO_{3}(aq)$

Hence, we can conclude that the statement precipitation reactions always occur when two aqueous solutions are mixed, is false.

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In a certain city, electricity costs $0.17 per kW·h. What is the annual cost for electricity to power a lamp-post for 5.50 hours

Anon25 [30]

Answer:

(a) = $34.123

(b) = $8.532

Explanation:

Cost of electricity = $0.17 per kW·h

(a) For a 100 watt bulb which is the same as 100/1000 or 0.1 kW, the cost per hour =

0.1 × 0.17 = $0.017/h

and for 5.5 hours = 0.017×5.5 = $0.0935

The annual cost, which is 365 days, we have

Annual cost = $0.0935 × 365 = $34.123

(b) For the energy efficient 25-watt bulb, we have

25/1000 = 0.025kW

Power cost per annum =

0.025kW×$0.17 per kW·h×5.5×365 = $8.532

Total cost of using the energy efficient fluorescent bulb is about $3.49

Total cost of using the energy efficient bulb = $8.532 + $3.49 = $12.02

Total cost of incandescent bulb = $35.02 while total cost of energy efficient bulb is = $12.02

$12.02 <$35.02

Additional cost of fluorescent bulb is justified

8 0

3 years ago

When writing equations the mass on the left of the arrow must

sp2606 [1]

Answer:

When writing equation the mass on left side of equation must be equal to the mass on right side. True

Explanation:

The chemical reactions always follow the law of conservation of mass.

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

Explanation:

This law was given by french chemist Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

For example:

In photosynthesis reaction:

6CO₂ + 6H₂O + energy → C₆H₁₂O₆ + 6O₂

there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass because total mass is equal on both side of equation.

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3 years ago

A teacher gives students four liquids commonly found in the kitchen - vinegar, apple juice, dish detergent, and milk - and pH in

VMariaS [17]

Answer:

1. Comparative

2. Independent variable

3. The pH is the Dependent variable

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3 years ago

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The discovery of the atomic nucleus, or perhaps better stated the development of theory of the nucleus, is credited to Ernest Ru

Greeley [361]

Answer:

Both of the studies said that the mass of the atom is centered in the nucleus, which is positive, and there are electrons (negative particles) orbiting it. So, Rutheford and Nagaoka discovered that the atom can be divisible and it has an empty space.

But, in the model of Nagaoka, the nucleus was huge, and for Rutherford, the nucleus was really small, and the mass was concentrated. By his experiment with the gold sheets, the theory was appropriated. That's why Rutherford is credited with the discovery of the nucleus. Nagaoka was incorrect in his suppositions.

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3 years ago

In which set do all elements tend to form anions in binary ionic compounds? li, na, k n, o, i c, s, pb k, fe, br?

pav-90 [236]

Atoms or molecule after gaining of electron possesses negative charge and is known as anion.

For the given sets:

$Li, Na, K$

The given elements are alkali metals and have tendency to lose electrons easily and form cations.

$N, O, I$

The given elements are non-metals and are electronegative. So, they gain electrons easily and form anion.

$C, S, Pb$

Carbon has tendency to form bond by sharing of electrons, Sulfur has tendency to gain electrons and form anion whereas Lead has tendency to lose electron.

$K, Fe, Br$

Potassium and Iron has tendency to lose electron and form cation whereas Bromine has tendency to gain electron to form anion.

Hence, from the given sets, all elements of set: $N, O, I$ have tendency to form anions in binary ionic compounds.

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3 years ago

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