Properties of water equal to that of the hydrogen ion (), which gives a pH of 7 at 25 °C. Action of water on rock over long periods of time typically leads to weathering and water erosion, physical processes that convert solid rocks and minerals into soil and sediment, but under some conditions chemical reactions with water occur as well, resulting in metasomatism or mineral hydration, a type of chemical alteration of a rock which produces clay minerals. It also occurs when Portland cement hardens. Water ice can form clathrate compounds, known as clathrate hydrates, with a variety of small molecules that can
Water crisis in the Democratic Republic of the Congo water scarcity problem, hindering development in the country. Article 48 of the 2006 Constitution of the DRC recognizes the human right to water. The rehabilitation and development of the water sector is a priority to which the national government committed itself in the Growth and Poverty Reduction Strategies and to which it agreed as part of the international framework of the UN Millennium Development Goals. The DRC is the most water-rich country in Africa. It accounts for approximately 52 percent of Africa's surface water reserves and 23 percent of Africa's internal renewable water resources. The internal renewable freshwater resources per