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3 years ago

How much heat is required to raise the temperature of 65.8 grams of water from 31.5ºC to 46.9ºC?

Chemistry

1 answer:

vodomira [7]3 years ago

3 0

Answer: 1,013.32 cal × 4.18 J/cal = 4,235.68 J

Explanation:

1) Data:

Water ⇒ C = 1 cal/g°C

m = 65.8 g

Ti = 31.5°C

Tf = 36.9°C

Heat, Q = ?

2) Formula:

Q = mCΔT

3) Calculations:

Q = 65.8g × 1 cal/g°C × (46.9°C - 31.5°C) = 1,013.2 cal

4) You can convert from calories to Joules using the conversion factor:

1 cal = 4.18 J

⇒ 1,013.32 cal × 4.18 J/cal = 4,235.68 J

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A chemistry student needs to standardize a fresh solution of sodium hydroxide. She carefully weighs out 385.mg of oxalic acid H2

Vlada [557]

Answer:

The molarity of the sodium hydroxide solution is 0.0692 M

Explanation:

Step 1: Data given

Mass of H2C2O4 = 385 mg = 0.385 grams

volume = 250 mL = 0.250 L

Volume of NaOH = 123.7 mL = 0.1237 L

Molar mass H2C2O4 = 90.03 g/mol

Step 2: The balanced equation

2NaOH + H2C2O4 → Na2C2O4 + 2H2O

Step 3: Calculate moles H2C2O4

Moles H2C2O4 = mass H2C2O4 / molar mass H2C2O4

Moles H2C2O4 = 0.385 grams / 90.03 g/mol

Moles H2C2O4 = 0.00428 moles

Step 4: Calculate molarity of H2C2O4

Molarity H2C2O4 = moles / volume

Molarity H2C2O4 = 0.00428 moles / 0.250 L

Molarity H2C2O4 = 0.01712 M

Step 5: Calculate molarity of NaOH

2*Ca*Va = n*Cb*Vb

⇒ with Ca = Molarity of H2C2O4 = 0.01712 M

⇒ Va = volume of H2C2O4 = 0.250 L

⇒Cb = molarity of NaOH = TO BE DETERMINED

⇒ Vb = volume of NaOH = 0.1237 L

Cb = (2*0.01712*0.250)/0.1237

Cb = 0.0691 M

The molarity of the sodium hydroxide solution is 0.0692 M

4 0

3 years ago

What quantity of heat is required to raise the temperature of 460g of aluminum from 15C to 85C?

Hoochie [10]

Answer:

Q = 28.9 kJ

Explanation:

Given that,

Mass of Aluminium, m = 460 g

Initial temperature, $T_i=15^{\circ} C$

Final temperature, $T_f=85^{\circ}$

We know that the specific heat of Aluminium is 0.9 J/g°C. The heat required to raise the temperature is given by :

$Q=mc\Delta T\\\\Q=mc(T_f-T_i)\\\\Q=460\ g\times 0.9\ J/g^{\circ} C\times (85-15)^{\circ} C\\\\Q=28980\ J\\\\\text{or}\\\\Q=28.9\ kJ$

So, 28.9 kJ of heat is required to raise the temperature.

6 0

4 years ago

The correct sequence where reactivity towards oxygen increases.

ziro4ka [17]

Answer:

Option D is good to go!

Explanation: as per the reactivity series more reactive substances will react with the counterpart substance.The most reactive substance here is calcium while the least reactive is aluminium, the magnesium comes in between.As per their reactivity, these substances will react with oxygen.

Explanation:

3 0

3 years ago

What is a molecular formula?

polet [3.4K]

The symbolic representation of its compound and its composition.

or a chemical formula that indicates the kinds of atoms and the number of each kind in a molecule of a compound.
ANSWER IS B

5 0

3 years ago

How many moles of water as a gas can be formed 2.45 L

Alex17521 [72]

Answer:

0.11mole

Explanation:

Let us assume that the condition is at standard temperature and pressure(STP);

Given parameters:

Volume of water = 2.45L

Unknown:

Number of moles found in this volume of water = ?

Solution;

At STP;

Number of moles = $\frac{volume of gas}{22.4}$

Input the parameters and solve;

Number of moles of water = $\frac{2.45}{22.4}$ = 0.11mole

The number of moles of water found is 0.11mole

4 0

3 years ago