What is often mistakenly regarded as being based on science?

Gallium is a solid metal at room temperature but melts at 29.9 °C. If you hold gallium in your hand, it melts from body heat. Ho

matrenka [14]

Answer: 4.56 Joules

Explanation:-

The quantity of heat required to raise the temperature of a substance by one degree Celsius is called the specific heat capacity.

$Q=m\times c\times \Delta T$

Q = Heat absorbed = ?

m= mass of substance = 2.5 g

c = specific heat capacity = $0.372J/g^0C$

Initial temperature = $T_i$ = 25.0°C

Final temperature = $T_f$ = 29.9°C

Change in temperature , $\Delta T=T_f-T_i=(29.9-25.0)^0C=4.90^0C$

Putting in the values, we get:

$Q=2.5\times 0.372\times 4.90^0C$

$Q=4.56J$

The heat absorbed by gallium must be 4.56 Joules

7 0

3 years ago

How many atoms are in 45.22 moles of strontium

AleksandrR [38]

Answer:

272.31× 10²³ atom of strontium

Explanation:

Given data:

Number of moles of strontium = 45.22 mol

Number of atoms = ?

Solution:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance. The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms

45.22 mol × 6.022 × 10²³ atom / 1 mol

272.31× 10²³ atom

7 0

2 years ago

In a double-replacement reaction, the _____.

givi [52]

In a double-replacement reaction, the _____.?

There are many more interesting things to ask about double replacement reactions than are contained in the list given here. But the only correct choice is:

C.reactants are two ionic compounds

8 0

3 years ago

Read 2 more answers

Planets close to a star will have __ orbital velocities than planets farther from a star.

Naddika [18.5K]

Answer:

The closer a planet is to the Sun, the stronger the Sun's gravitational pull on it, and the faster the planet moves. The farther it is from the Sun, the weaker the Sun's gravitational pull, and the slower it moves in its orbit.

5 0

3 years ago

C2H5OH(l) + 3O2(g) → 2CO2(g) + 3H2O(l), ΔH = –1.37 × 103 kJ For the combustion of ethyl alcohol as described in the above equati

babymother [125]

Answer:

The true statements are: I. The reaction is exothermic.

II. The enthalpy change would be different if gaseous water was produced.

Explanation:

The given chemical reaction: C₂H₅OH(l) + 3O₂(g) → 2CO₂(g) + 3H₂O(l), ΔH= -1.37×10³kJ

1. In an exothermic reaction, heat or energy is released from the system to the surrounding. Thus for an exothermic process the change in enthalpy is less than 0 or negative (ΔH < 0) .

Since the enthalpy change for a combustion reaction is negative. Therefore, the given reaction is exothermic.

2. The change in enthalpy (ΔH) of a reaction is equal to difference of the sum of standard enthalpy of formation (ΔHf°) of the products and the reactants.

ΔHr° = ∑ n.ΔHf°(products) − ∑ n.ΔHf°(reactants)

As the value of ΔHf° of water in gaseous state and liquid state is not the same.

Therefore, the enthalpy change of the reaction will be different, if gaseous water was present instead of liquid water.

3. An oxidation-reduction reaction or a redox reaction involves simultaneous reduction and oxidation processes.

The given chemical reaction, represents the combustion reaction of ethanol.

Since combustion reactions are redox reactions. Therefore, the given combustion reaction is an oxidation-reduction reaction.

4. According to the ideal gas equation: P.V =n.R.T

Volume (V) ∝ n (number of moles of gas)

Since the number of moles (n) of gaseous reactants is 3 and number of moles of gaseous (n) products is 2.

Therefore, the volume occupied by 3 moles of the reactant gaseous molecules will be more than 2 moles product gaseous molecules.

3 0

3 years ago