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Pepsi [2]
2 years ago
15

Urea is a common fertilizer with the formula CO(NH2)2 that is sometimes used as a chemical de-icer for icy road surfaces in the

winter months. Adding a solute to a solvent causes the freezing point to be lowered and allows the solvent to remain liquid at lower temperatures. The value of Kf for water is 1.86°C/m, and its normal freezing point is 0.00°C. Urea is a nonvolatile nonelectrolyte solute. What molality of urea is required to lower the freezing point of ice water by 1.13°C?
Chemistry
1 answer:
nordsb [41]2 years ago
4 0

Answer:

The answer to your question is  molality = 0.61

Explanation:

Freezing point is the temperature at which a liquid turns into a solid if a solute is added to a solution, the freezing point changes.

Data

Kf = 1.86 °C/m

molality = ?

ΔTc = 1.13°C

Formula

ΔTc = kcm

Solve for m

m = ΔTc/kc

Substitution

m = 1.13 / 1.86

Simplification and result

m = 0.61

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How many milliliters of 0.02 M HCl are needed to react completely with 100 mL of 0.01 M NaOH?
serious [3.7K]
The reaction of HCl and NaOH is HCl + NaOH = NaCl + H2O. So the mole number of HCl and NaOH is equal. So the volume of HCl =0.01*0.1/0.02=0.05 L =50 ml. So the answer is D).
3 0
2 years ago
Read 2 more answers
Ron and Hermione begin with 1.50 g of the hydrate copper(II)sulfate ∙ x-hydrate (CuSO4 ∙ xH2O), where x is an integer. Part of t
Gwar [14]

Answer

5

Explanation:

We can go about this using the percentage compositions.

First, we calculate the percentage composition of the copper sulphate. This is obtainable by using the mass.

0.96/1.5 * 100 = 64%

Hence the percentage by mass of the water present is 36%

The molar mass of the anhydrous sulphate is 64 + 32 +4(16) = 160g/mol

The molar mass of the water is 2(1) + 16 = 18g/mol

Not forgetting that it is in multiples of x, the total molar mass of the water is 18x moles

The total mass of the copper sulphate hydrate is 160+ 18x

Now how do we get x? Like it is said earlier, the percentage composition is constant.

Hence, 64/100 * (160 + 18x) = 160

16000 = 64(160 + 18x)

16000 = 10,240 + 1152x

16,000 - 10,240 = 1152x

1152x = 5760

x = 5760/1152

x = 5

7 0
2 years ago
The pressure and temperature inside a bike tire is 10 atm and 10k respectively. What will the pressure become in the tire when t
igomit [66]

Answer:

P_2=20atm

Explanation:

Hello,

In this case, we apply the Gay-Lussac's law which allows us to understand the pressure-temperature behavior as a directly proportional relationship:

\frac{P_1}{T_1}= \frac{P_2}{T_2}

Thus, we solve for the final pressure P2 to obtain it as shown below:

P_2=\frac{P_1T_2}{T_1}=\frac{10atm*20K}{10K} \\\\P_2=20atm

Hence, we notice that the temperature doubles as well as the pressure.

Best regards.

3 0
2 years ago
Given that the rate constant is 4.0×10−4 m−1 s−1 at 25.0 ∘c and that the rate constant is 2.6×10−3 m−1 s−1 at 42.4 ∘c, what is t
stepladder [879]
So here's how you find the answer:

Given: (rate constants)

K₁ = 4.0 x 10⁻⁴ M⁻¹s⁻¹.
T₁ = 25.0 C = 293 K.
k₂ = 2.6 x10⁻³ M⁻¹s⁻¹.
T₂ = 42.4 C = 315.4 K.
R = 8,314 J/K·mol.

Use the equation:

ln(k₁/k₂) = Ea/R (1/T₂ - 1/T₁).

Transpose:

Ea = R·T₁·T₂ / (T₁ - T₂) · ln(k₁/k₂)

Substitute within the given transposed equation:

<span>Ea = 8,314 J/K·mol · 293 K · 315.4 K ÷ (293 K - 315.4 K) · ln (4.0 x 10⁻⁴ M⁻¹s⁻¹/ 2.6 x 10⁻³ M⁻¹s⁻¹).
</span>
Continuing the solution we get:

<span>Ea = 768315 J·K/mol ÷ (-22,4 K) * (-1.87)
</span>
The value of EA is:

<span>Ea = 64140.58 J/mol ÷ 1000 J/kJ = 64.140 kJ/mol.</span>


4 0
1 year ago
The atoms of a certain element each contain 19 protons and 1 valence electron. Which statement correctly identifies this element
Leya [2.2K]

Answer

its a potassium elements

Explanation:

K 2,8,8,1     period num 4

                  group 1A

or 1s1 ,2s2 2p6, 3s1

its a metal reacted  rapidly with water to form a colorless basic solution of potassium hydroxide (KOH) and hydrogen gas (H2). The reaction continues even when the solution becomes basic. The resulting solution is basic because of the dissolved hydroxide. The reaction is exothermic.

3 0
1 year ago
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