How much energy must a 10 gram block of ice gain in order to melt ?

Which of the following is NOT a clue that a chemical change has occurred? * 1 point Sugar turns blackish-brown as it is heated.

Vladimir [108]

Answer:

The answer is Steam is produced when water is heated. The color does not change, a precipice is not formed, and the odor does not change!

5 0

4 years ago

Flourine is found to undergo 10% radioactivity decay in 366 minutes determine its halflife

yuradex [85]

Answer:

$\boxed{\text{2408 min}}$

Explanation:

The integrated rate law for radioactive decay is

$\ln\dfrac{N_{0}}{N_{t}} = kt$

1. Calculate the decay constant

$\begin{array}{rcl}\ln \dfrac{100}{90} & = & k \times 366\\\\1.054 & = & 366k\\\\k & = & \dfrac{1.054 }{366}\\\\k & = & 2.879 \times 10^{-4} \text{ min}^{-1}\\\end{array}\\\\$

2. Calculate the half-life

$t_{\frac{1}{2}} = \dfrac{\ln2}{k}\\\\t_{\frac{1}{2}} = \dfrac{\ln2}{2.879 \times 10^{-4} \text{ min}^{-1}} = \text{2408 min}\\\\\text{The half-life for decay is } \boxed{\textbf{2408 min}}$

8 0

3 years ago

Why do elements form compounds? What elements never form compounds and why?

Alja [10]

Answer:

Elements form compounds to satisfy the octet rule. Noble gasses never form compounds because they already satisfy the octet rule.

Explanation:

The octet Rule is the theory that an element will attempt to gain a valence of 8 by binding with another element in it's vicinity. This can happen in a variety of ways, but the main thing to remember is that they will take the "shortest path" to 8(I.e an element will sometimes lose an electron or 2 if it has a valence 1 or 2 to loop back around to 8, while an element with a valence of 6 or 7 will attempt to gain 2 or 1 electrons).

Valence of elements can be counted by group in the image attached.

Group 1 has a valence of 1, Group 2 has a valence of 2, then we move to group 13 which has a valence of 3, group 14 has a valence of 4, group 15 has a valence of 5, group 16 has 6, group 17 has 7, and group 18 is the noble gasses which have 8.

7 0

3 years ago

Sodium hydroxide (NaOH) and hydrochloric acid (HCl) combine to make table salt (NaCl) and water (H2O). Which equation is balance

Art [367]

The equation that is balanced among the given options is the first equation NaOH + HCl → NaCl + H2O

From the question,

We are to determine which of the options gives a balanced equation for the reaction between sodium hydroxide (NaOH) and hydrochloric acid (HCl) to make table salt (NaCl) and water (H₂O)

To do this, we will check which of the given equations is balanced, by checking the equations one after the other.

First, we will define what is meant by balanced equation.

Balanced equations are those whose coefficients result in equal numbers of atoms for each element in the reactants and products

For NaOH + HCl → NaCl + H2O

On the reactants side

Na = 1

O = 1

H = 2

Cl = 1

On the products side

Na = 1

O = 1

H = 2

Cl = 1

Since equal number of atoms of each element are present at both the reactants and products sides, then the equation is balanced

For 2NaOH + 2HCl → 2NaCl + H2O

On the reactants side

Na = 2

O = 2

H = 4

Cl = 1

On the products side

Na = 2

O = 1

H = 2

Cl = 2

The number of atoms of each element present at the reactants side and that present at products side are not equal.

∴ The equation is not balanced

For 2NaOH + HCl → NaCl + H2O

On the reactants side

Na = 2

O = 2

H = 3

Cl = 1

On the products side

Na = 1

O = 1

H = 2

Cl = 1

The number of atoms of each element present at the reactants side and that present at products side are not equal.

∴ The equation is not balanced

For NaOH + 2HCl → NaCl + H2O

On the reactants side

Na = 1

O = 1

H = 2

Cl = 2

On the products side

Na = 1

O = 1

H = 2

Cl = 1

The number of atoms of each element present at the reactants side and that present at products side are not equal.

∴ The equation is not balanced

Hence, the equation that is balanced is the first equation NaOH + HCl → NaCl + H2O

Learn more here: brainly.com/question/17015942

6 0

2 years ago

Read 2 more answers

Which skier will have a greater potential energy? Justify your answer.

pochemuha

Answer: Skier 1 will have more potential energy because he is higher than skier 2

Explanation: Gravitational potential energy is the energy possessed by a body by virtue of its position or height.

P.E= $m\times g\times h$

m= mass of the body

g= acceleration due to gravity

h= height of body

Thus if the masses of two bodies are same, the one with greater height possess greater potential energy.

6 0

4 years ago