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Juliette [100K]
3 years ago
14

A school has 8 period in a day such the each periods is of 35 minutes.lf the number of period is reduced to 7, then how long wou

ld each period be?​
Chemistry
1 answer:
scZoUnD [109]3 years ago
5 0

Answer:

45 minutes about

Explanation:

i think because i have 7 periods with 45 minutes each

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When 15.3 g of sodium nitrate, NaNO3,was dissolved in water in a calorimeter, the temperature fell from 25.00oC to 21.56oC. If t
satela [25.4K]

Answer:

20.468 kilo Joules is the enthalpy change when one mole of sodium nitrate dissolves.

Explanation:

Heat lost by solution ad calorimeter = Q

Heat capacity of solution ad calorimeter = C = 1071 J/°C

Change in temperature = ΔT = 21.56°C - 25.00°C = -3.44°C

Q=C\times Delta T

Q=1071 J/^oC\times (-3.44^oC)=-3,684.24 J

Heat gained by sodium nitrate = -Q = -(-3,684.24 J)=3,684.24 J

Moles of sodium nitrate = \frac{15.3 g}{85 g/mol}=0.18 mol

When 0.18 mole of sodium nitrate was dissolved in water 3,684.24 joulesof heat was absorbed by it.

Then heat absorbed by 1 mole of sodium nitrate :

\frac{3,684.24 J}{0.18}=20,468 J=20.468 kJ

1 J = 0.001 kJ

20.468 kilo Joules is the enthalpy change when one mole of sodium nitrate dissolves.

8 0
3 years ago
For each pair of salts, determine which of the salts, if any, would be expected to be more soluble in acidic solution than in pu
gogolik [260]

Answer:

AgNO2

Explanation:

The question asks to know which of these two insoluble salts is expected to be more soluble in acidic solution than in pure water.

To answer this question specifically, we need to know if the anions contained in the insoluble salt is a conjugate of a weak acid or that of a weak base.

Generally, the solubility of insoluble salts that contain anions which are conjugates of weak acids increases in the presence of an acidic solution than in water. While, the solubility of insoluble salts that contain anions which are conjugates of strong acids decreases in the presence of an acidic solution.

Having said this, AgNO2 contains NO2 which is the conjugate base of the Trioxonitrate iii acid which is a weak acid. Hence, it is expected to be stronger in acidic solution than in water.

4 0
3 years ago
A student adds sugar to a cup of iced tea and a cup of hot tea. She notices that the time needed for the sugar to dissolve in ea
Natali [406]

Explanation:

the experiment conducted is the student adds sugar to a cup of iced tea and a cup of hot tea. She notices that the time needed for the sugar to dissolve in each cup is different. She thinks this has something to do with the temperature of the tea

hypothesis: If the student puts the sugar in both glasses of tea, then the sugar in the hot tea should dissolve quicker.

4 0
3 years ago
An excess of oxygen reacts with 451.4 g of lead, forming 374.7 g of lead(II) oxide. Calculate the percent yield of the reaction.
Stels [109]

Answer: The percent yield of the reaction is 77.0 %

Explanation:

2Pb+O_2\rightarrow 2PbO

\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}

\text{Number of moles of lead}=\frac{451.4g}{207.2g/mol}=2.18moles

\text{Number of moles of lead oxide}=\frac{374.7g}{223.2g/mol}=1.68moles

According to stoichiometry:

2 moles of Pb produces = 2 moles of PbO_2

2.18 moles of Pb is produced by=\frac{2}{2}\times 2.18=2.18moles of PbO_2

Mass of PbO_2 =moles\times {\text {Molar mass}}=2.18\times 223.2g/mol=486.6

percent yield =\frac{374.7g}{486.6g}\times 100=77.0\%

3 0
3 years ago
Match the term to its description
NeTakaya

<u>Answer :</u>

Chemical energy - D) Potential energy stored in the bonds between atoms

Electrical energy - C) The movement of an electrical charge

Radiant energy - B) Electromagnetic energy that travels in waves

Thermal energy - A) Internal energy caused by vibrations of atoms and  molecules

<u>Explanation :</u>

Chemical energy : It is the type of energy in which the potential energy is stored in the bonds between the atoms.

Electrical energy : It is a type of energy in which the electrical charge are moved.

Radiant energy : It is a type of energy in which the electromagnetic energy travels in the waves.

Thermal energy : It is a type of energy in which an internal energy caused by the vibrations of atoms and the molecules.

4 0
4 years ago
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