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andreev551 [17]
3 years ago
9

A 2-kW resistance heater in a water heater runs for 3 hours to raise the water temperature to the desired level. Determine the a

mount of electric energy used in both kWh and kJ.
Physics
1 answer:
nexus9112 [7]3 years ago
7 0

Power(p) = 2kW

Time(t)= 3 h

Work done(w) = ?

p = w / t

w = p × t

w = 2kW × 3 h

w = 6kWh

Converting 6kWh to Joules,

6kWh

6×(10^3)h ( k = 10^3 )

6×10^3×(60×60) ( 1 hour = 60 × 60 sec)

2.2×10^7 J in 2 significant figures

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What is the density of 53.4 wt queous naoh solution if 16.7 ml of the solution diluted to 2.00 l gives 0.169 m naoh?
vampirchik [111]

The density of 53.4 wt aqueous NaOH solution is 0.809 g/ml

Given data:

  • The mass percent of NaOH is 53.4.
  • Volume of NaOH diluted is 16.7 ml.
  • The volume of diluted solution is 2.00 L =2000 ml.
  • Concentration of diluted solution is 0.169 M.

First, we find the initial concentration of NaOH by using the following formulae,

M₁V₁ = M₂V₂

Where,

M₁ is the initial molarity of NaOH

M₂ is the molarity after dilution

V₁ is the initial volume of NaOH

V₂ is the final volume after dilution.

Substituting the values,

M₁ × 16.7 ml = 0.169 M × 2000 ml,

M₁ =  \frac{0.169 M *2000 ml}{16.7 ml}

M₁ = 20.2 M.

Thus, the initial concentration of NaOH is 20.2 M.

we know, 1 M solution contains 1 mol of substance present in 1 L solution,

Thus, 20.2 M solution will have 20.2 mols of NaOH.

Now, we can find the mass of NaOH by using the number of moles and molar mass.

  • molar mass of NaOH is 40 g/mol.

Mass = no. of moles × molar mass

= 20.2 mol × 40 g/mol

= 808 g.

Thus, the mass of NaOH is 808g.

53.4 wt of NaOH means 53.4 g of NaOH in a 100 g solution,

Thus, 808 g of NaOH will be present in ,

⇒ \frac{53.4 g NaOH}{100 g solution} = \frac{808 g NaOH}{x g solution}

⇒ 1513.1 g

Now, Convert the grams of NaOH to milliliters, using the density of NaOH at room temperature.

  • The density of NaOH at room temperature is 1.515 g/ml,

Density = \frac{mass}{volume}

⇒ 1.515 g/mol = \frac{1513.1 g}{volume}

⇒ volume = \frac{1513.1 g}{1.515 g/mol}

⇒ volume = 998.7 ml.

Thus, the volume of NaOH is 998.7 ml.

Hence, we know,

  • the mass of NaOH is 808 g
  • the volume of NaOH is 998.7 ml

Substituting the values,

Density = 808 g / 998.7 g/ml

⇒ Density = 0.809 g/ml

Thus, the density of 53.4 wt aqueous NaOH is 0.809 g/ml.

To learn more about Density here

brainly.com/question/15164682

#SPJ4

3 0
2 years ago
22 points! if right I will give brainlyest
hammer [34]
<h3>♫ - - - - - - - - - - - - - - - ~Hello There!~ - - - - - - - - - - - - - - - ♫</h3>

➷ The dependent variable is the variable that is being measured.

In this case, the dependent variable is the amount of force required to stretch the spring.

<h3><u>✽</u></h3>

➶ Hope This Helps You!

➶ Good Luck (:

➶ Have A Great Day ^-^

↬ ʜᴀɴɴᴀʜ ♡

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