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satela [25.4K]
4 years ago
9

Which element listed below is considered an alkaline earth metal?

Chemistry
1 answer:
schepotkina [342]4 years ago
5 0
<span>Which element listed below is considered an alkaline earth metal? 
</span>B) Magnesium
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State whether the following statements are true or false (with justification). (a) 1 mol of N2 has more molecules than 1 mol of
MAVERICK [17]

Answer:

A. False.

Every substance contains the same number of molecules i.e 6.02x10^23 molecules

B. False.

Mass conc. = number mole x molar Mass

Mass conc. of 1mole of N2 = 1 x 28 = 28g

Mass conc. of 1mol of Ar = 1 x 40 = 40g

The mass of 1mole of Ar is greater than the mass of 1mole of N2

C. False.

Molar Mass of N2 = 2x14 = 28g/mol

Molar Mass of Ar = 40g/mol

The molar mass of Ar is greater than that of N2.

Explanation:

7 0
3 years ago
The number of atoms or molecules in a mole is known as the __________ constant.
AnnZ [28]

Answer: Avogrado's Constant

Explanation:

One mole of a substance is equal to 6.022 × 10²³ units of that substance (such as atoms, molecules, or ions). The number 6.022 × 10²³ is known as Avogadro's number or Avogadro's constant. The concept of the mole can be used to convert between mass and number of particles.

7 0
3 years ago
Compute the percentage of error to the nearest tenth in the student’s calculation if the actual specific heat value for aluminum
Artist 52 [7]

Complete Question:

1. A block of aluminum with a mass of 140 g is cooled from 98.4°C to 62.2°C with a release of 4817 J of heat. From these data, calculate the specific heat of aluminum.

a. Compute the percentage of error to the nearest tenth in the student's calculation if the actual specific heat value for aluminum is 0.9 J/g°C

Answer:

Percent error = 55.56 %

Explanation:

Given the following data;

Mass = 140 grams

Initial temperature = 62.2°C

Final temperature = 98.4°C

Quantity of heat = 4817 Joules.

To find the specific heat capacity;

Heat capacity is given by the formula;

Q = mcdt

Where;

  • Q represents the heat capacity or quantity of heat.
  • m represents the mass of an object.
  • c represents the specific heat capacity of water.
  • dt represents the change in temperature.

dt = T2- T1

dt = 98.4 - 62.2

dt = 36.2°C

Making c the subject of formula, we have;

c = \frac {Q}{mdt}

Substituting into the equation, we have;

c = \frac {4817}{140*36.2}

c = \frac {4817}{5068}

<em>Specific heat capacity, = 0.95 J/g°C</em>

b. To find the percentage error;

Given the following data;

Actual specific heat capacity = 0.9 J/g°C

Experimental specific heat capacity = 0.95 J/g°C

Percent error can be defined as a measure of the extent to which an experimental value differs from the theoretical value.

Mathematically, it is given by this expression;

Percent \; error = \frac {experimental \;value - actual \; value}{ actual \;value} *100

Substituting into the formula, we have;

Percent \; error = \frac {0.95 - 0.9 }{ 0.9} *100

Percent \; error = \frac {0.5}{0.9} *100

Percent \; error = 0.5556 *100

<em>Percent error = 55.56 %</em>

5 0
3 years ago
A 2.49 g sample of aniline (C6H5NH2, molar mass = 93.13 g/mol) was combusted in a bomb calorimeter with a heat capacity of 4.25
Maslowich

The value of delta H° for aniline = 6415 Kj/mol

<u><em>calculation</em></u>

Step 1: find heat

Q (heat)  =  C (specific heat capacity)  x ΔT (change in temperature)

C= 4.25 kj/c°

ΔT = 69.8-29.5  = 40.3 c°

Q= 4.25 kj/c  x  40.3 c = 171.28 kj

Step 2:  find the moles of aniline

moles  = mass/molar  mass

= 2.49 g/ 93.13 g/mol =0.0267 moles

Step 3:  find delta H

171.28 kj/0.0267 mol = 6415 kj/mol

since the reaction is  exothermic  delta H = 6415 Kj/mol

4 0
2 years ago
Convert 0.00763 nL to L
Reptile [31]

Answer:

7.63\cdot10^{-12} L

Explanation:

Conversion problems could be solved using dimensional analysis for convenient use and understanding. Dimensional analysis is a technique of multiplying the measure we have by a fraction corresponding to some two equal measures in different units.

In order to apply dimensional analysis here, we firstly need to know that a prefix 'n' stands for 'nano', and nano means 10^{-9}. In this case, we have nanoliters. Using the prefix, we can find a relationship between nanoliter and liter:

1 nL = 10^{-9} nL

We may now apply dimensional analysis. Since we wish to convert into liters, we'll be multiplying the number we have in nL by a fraction that contains this relationship with liters in the numerator and nanoliters in the denominator, so that nL terms cancel out and we would obtain the final answer in liters:

0.00763 nL\cdot \frac{10^{-9} L}{1 nL}=7.63\cdot10^{-12} L

6 0
3 years ago
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