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3 years ago

How much heat is needed to change the temperature of 5g of water from 20 oC to 37 oC?

Chemistry

2 answers:

Dafna1 [17]3 years ago

5 0

Answer:

The answer to your question is Q = 355.64 J

Explanation:

Data

Heat = Q = ?

Temperature 1 = T1 = 20°C

Temperature 2 = T2 = 37°C

mass = m = 5 g

Specific heat = Cp = 4.184 J/g°C

Formula

Q = mCp(T2 - T1)

-Substitution

Q = (5)(4.184)(37 - 20)

-Simplification

Q = (5)(4.184)(17)

-Result

Q = 355.64 J

BabaBlast [244]3 years ago

4 0

The correct answer is 355.64 j

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A 25.0-mL sample of 0.150 M hydrazoic acid, HN3, is titrated with a 0.150 M NaOH solution. What is the pH after 13.3 mL of base

tamaranim1 [39]

Answer:

pH ≅ 4.80

Explanation:

Given that:

the volume of HN₃ = 25 mL = 0.025 L

Molarity of HN₃ = 0.150 M

number of moles of HN₃ = 0.025 × 0.150

number of moles of HN₃ = 0.00375 mol

Molarity of NaOH = 0.150 M

the volume of NaOH = 13.3 mL = 0.0133

number of moles of NaOH = 0.0133× 0.150

number of moles of NaOH = 0.001995 mol

The chemical equation for the reaction of this process can be written as:

$HN_3 + OH- ---> N^-_{3} + H_2O$

1 mole of hydrazoic acid react with 1 mole of hydroxide to give nitride ion and water

thus the new number of moles of HN₃ = 0.00375 - 0.001995 = 0.001755 mol

Total volume used in the reaction = 0.025 + 0.0133 = 0.0383 L

Concentration of $HN_3$ = $\dfrac{0.001755}{0.0383}$ = 0.0458 M

Concentration of $N^{-}_3$ = $\dfrac{ 0.001995 }{0.0383}$ = 0.0521 M

GIven that :

Ka = $1.9 x 10^{-5}$

Thus; it's pKa = 4.72

$pH =4.72 + log(\dfrac{ \ 0.0521}{0.0458})$

$pH =4.72 + log(1.1376)$

$pH =4.72 + 0.05598$

$pH =4.77598$

pH ≅ 4.80

3 0

3 years ago

Which has more mass: an armful of feathers or an armful of lead? which has more volume: a kilogram of feathers or a kilogram of

valina [46]

Mass is related to weight. It measures the resistance of the substance to acceleration when a net force is applied.
Therefore: armful of lead has more mass

volume measures the amount of 3-dimensional space that an object occupies.
Therefore: kilogram of feather has more volume as it is less dense.

density is the mass per unit volume. Since armful of lead has more mass than a handful of feathers, while kilogram of feather has more volume than a kilogram of lead.
Therefore: kilogram of lead has higher density.

8 0

3 years ago

What is true about resonance structures? Select the correct answer below: They are all different molecules. The interconvert wit

3241004551 [841]

Answer:

The correct answer is: <em>They each partially describe the bonding in a molecule.</em>

Explanation:

Some chemical molecules cannot be described completely by using only one Lewis structure. In these cases, we can describe the molecule by drawing 2 or more Lewis structures, and the structures are called <u>resonance structures</u>. The overall molecular structure is explained by all the resonance structures together. So, they each describe the bonding in the molecule only partially.

7 0

3 years ago

How many grams of hydrochloric acid are produced when 15.0 grams NaCl react with excess H2SO4 in the reaction

e-lub [12.9K]

Answer:

11.65 g

Explanation:

Amount of NaCl = 15.0 grams

amount of H₂SO₄ = Excess

mass of hydrochloric acid (HCl) = ?

Solution:

To solve this problem first we will look for the reaction that NaCl react with H₂SO₄

Reaction:

2NaCl + H₂SO₄ --------> 2 HCl + Na₂SO₄

As the H₂SO₄ is in excess so the amount of hydrochloric acid (HCl) depends on the amount of NaCl as it its act as limiting reactant.

Now if we look at the reaction

2NaCl + H₂SO₄ --------> 2HCl + Na₂SO₄

1 mol 2 mol

Now convert moles to mass

Then

Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol

Molar mass of HCl = 1 + 35.5 = 36.5 g/mol

So,

2NaCl + H₂SO₄ --------> 2HCl + Na₂SO₄

2 mol (58.5 g/mol) 2 mol (36.5 g/mol)

94 g 73 g

So if we look at the reaction; 94 g of NaCl gives with 73 g of hydrochloric acid (HCl) in a this reaction, then how many grams of hydrochloric acid (HCl) will produce from 15.0 g of NaCl

For this apply unity formula

94 g of NaCl ≅ 73 g of HCl

15.0 g of NaCl ≅ X g of HCl

By Doing cross multiplication

X g of HCl = 73 g x 15.0 g / 94 g

X g of HCl = 11.65 g

11.65 g of hydrochloric acid (HCl) will produce by 15.0 g of NaCl

7 0

3 years ago

What’s Nacl molar mass amount

Likurg_2 [28]

NaCl is made of Na and Cl

The molar mass of Na = 22.989 g/mol

The molar mass of Cl = 35.453 g/mol

Molar mass of NaCl = 22.989 + 35.453

= 58.44 g/mol

4 0

1 year ago