Answer:
Chemical change :has change in mass, heat is needed, new element is formed, hard to reverse.......
Physicalchange:does not have change in mass, heat is not necessary, no new element is formed, easy to reverse
Answer:
C
Explanation:
Because most lanfills are caused by industries who need fossil fuels to make energy that causes toxic gas and then landfills.
Answer:
There are many reasons to examine human cells and tissues under the microscope. Medical and biological research is underpinned by knowledge of the normal structure and function of cells and tissues and the organs and structures that they make up. In the normal healthy state, the cells and other tissue elements are arranged in regular, recognizable patterns. Changes induced by a wide range of chemical and physical influences are reflected by alterations in the structure at a microscopic level, and many diseases are characterized by typical structural and chemical abnormalities that differ from the normal state. Identifying these changes and linking them to particular diseases is the basis of histopathology and cytopathology, important specializations of modern medicine. Microscopy plays an important part in haematology (the study of blood), microbiology (the study of microorganisms including parasites and viruses), and more broadly in the areas of biology, zoology, and botany. In all these disciplines, specimens are examined under a microscope.
<em><u>hope</u></em><em><u> </u></em><em><u>it</u></em><em><u> </u></em><em><u>helps</u></em><em><u> </u></em>
The balanced chemical reaction is expressed as:
<span>4hcl(g)+o2(g)→2h2o(l)+2cl2(g)
To determine the percent yield of the reaction, we need to calculate for the theoretical yield. This is the maximum amount of the product that can be produced from the reaction given the initial amounts of the reactants. First, we identify the limiting reactant as follows:
</span><span>63.1 g of hcl ( 1 mol / 36.46 g ) ( 1 mol O2 / 4 mol HCl) ( 32 g / mol) = 13.85 g O2
17.2 g of o2 ( 1 mol / 32 g ) ( 4 mol HCl / 1 mol O2) ( 36.46 g / mol) = 78.39 g HCl
Therefore, the limiting reactant would be HCl. We use the value for the HCl to calculate for the theoretical yield.
</span>63.1 g of hcl ( 1 mol / 36.46 g ) ( 2 mol Cl2 / 4 mol HCl) ( 70.9 g / mol ) = 61.35 g Cl2
Percent yield = actual / theoretical x 100
= 59.6 / 61.35 x 100
= 97.1%
